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Search: a006046 -id:a006046
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Values of n such that A006046(n)/n^theta, where theta=log(3)/log(2), is a local minimum, computed according to Harborth's recurrence.
+20
10
1, 3, 5, 11, 21, 43, 87, 173, 347, 693, 1387, 2775, 5549, 11099, 22197, 44395, 88789, 177579, 355159, 710317, 1420635, 2841269, 5682539, 11365079, 22730157, 45460315, 90920629, 181841259, 363682519, 727365037, 1454730075
CROSSREFS
Cumulative minima of A006046(n)/n^theta, where theta=log(3)/log(2), is a local minimum.
+20
8
1, 3, 5, 11, 21, 43, 87, 171, 173, 347, 693, 1387, 2775, 5547, 5549, 11099, 22197, 44395, 88789, 177579, 355159, 710315, 710317, 1420635, 2841269, 5682539, 11365079, 22730155, 22730157, 45460315, 90920629, 181841259, 363682519
CROSSREFS
a(n) = 2*A006046(n) + 1.
+20
4
1, 3, 7, 11, 19, 23, 31, 39, 55, 59, 67, 75, 91, 99, 115, 131, 163, 167, 175, 183, 199, 207, 223, 239, 271, 279, 295, 311, 343, 359, 391, 423, 487, 491, 499, 507, 523, 531, 547, 563, 595, 603, 619, 635, 667, 683, 715, 747, 811, 819, 835, 851, 883, 899, 931, 963
CROSSREFS
a(n) = A006046(A077465(n)).
+20
3
1, 5, 11, 37, 103, 317, 967, 2869, 8639, 25853, 77623, 232997, 698735, 2096461, 6288871, 18867125, 56600351, 169802077, 509408279, 1528220741, 4584666319, 13753990765, 41261980487, 123785957845, 371357840767, 1114073555069
CROSSREFS
a(n) = b(n+2) + b(n), where b(n) = A006046(n) is the sequence defined by b(0)=0, b(1)=1, b(n) = 2*b((n-1)/2) + b((n+1)/2) for n =3,5,7,... and b(n) = 3*b(n/2) for n =2,4,6,....
+20
1
3, 6, 12, 16, 24, 30, 42, 48, 60, 66, 78, 86, 102, 114, 138, 148, 168, 174, 186, 194, 210, 222, 246, 258, 282, 294, 318, 334, 366, 390, 438, 456, 492, 498, 510, 518, 534, 546, 570, 582, 606, 618, 642, 658, 690, 714, 762, 782, 822, 834, 858, 874, 906, 930, 978
FORMULA
a(n) = A006046(n+2) + A006046(n) for n>=1.
CROSSREFS
Cf. A006046.
a(n) = (n+1)^2 - A006046(n+1).
+20
1
0, 1, 4, 7, 14, 21, 30, 37, 52, 67, 84, 99, 120, 139, 160, 175, 206, 237, 270, 301, 338, 373, 410, 441, 486, 529, 574, 613, 662, 705, 750, 781, 844, 907, 972, 1035, 1104, 1171, 1240, 1303, 1380, 1455, 1532, 1603, 1684, 1759, 1836, 1899, 1992, 2083, 2176, 2263
CROSSREFS
a(0)=0; for n >= 1, a(n) = f(n) - 2*f(floor((n-1)/2)), where f(n) = A006046(n).
+20
1
0, 1, 3, 3, 7, 5, 9, 9, 17, 11, 15, 15, 23, 19, 27, 27, 43, 29, 33, 33, 41, 37, 45, 45, 61, 49, 57, 57, 73, 65, 81, 81, 113, 83, 87, 87, 95, 91, 99, 99, 115, 103, 111, 111, 127, 119, 135, 135, 167, 139, 147, 147, 163, 155, 171, 171, 203, 179, 195, 195, 227, 211, 243, 243, 307, 245, 249, 249, 257
EXAMPLE
The rows are a subset of the rows of Pascal's triangle A007318 read mod 2 (see A006943). The binary weights of these rows are given by A001316, whose partial sums are A006046, and the formula in the definition follows easily from this.
MAPLE
f:=proc(n) option remember; # A006046
CROSSREFS
Gould's sequence: a(n) = Sum_{k=0..n} (binomial(n,k) mod 2); number of odd entries in row n of Pascal's triangle (A007318); a(n) = 2^A000120(n).
(Formerly M0297 N0109)
+10
199
1, 2, 2, 4, 2, 4, 4, 8, 2, 4, 4, 8, 4, 8, 8, 16, 2, 4, 4, 8, 4, 8, 8, 16, 4, 8, 8, 16, 8, 16, 16, 32, 2, 4, 4, 8, 4, 8, 8, 16, 4, 8, 8, 16, 8, 16, 16, 32, 4, 8, 8, 16, 8, 16, 16, 32, 8, 16, 16, 32, 16, 32, 32, 64, 2, 4, 4, 8, 4, 8, 8, 16, 4, 8, 8, 16, 8, 16, 16, 32, 4, 8, 8, 16, 8, 16, 16, 32
FORMULA
Sum_{k=0..n-1} a(k) = A006046(n).
CROSSREFS
For partial sums see A006046. For first differences see A151930.
Number of "ON" cells at n-th stage in the "Ulam-Warburton" two-dimensional cellular automaton.
+10
91
0, 1, 5, 9, 21, 25, 37, 49, 85, 89, 101, 113, 149, 161, 197, 233, 341, 345, 357, 369, 405, 417, 453, 489, 597, 609, 645, 681, 789, 825, 933, 1041, 1365, 1369, 1381, 1393, 1429, 1441, 1477, 1513, 1621, 1633, 1669, 1705, 1813, 1849, 1957, 2065, 2389, 2401, 2437, 2473
FORMULA
For asymptotics see the discussion in the comments in A006046. - N. J. A. Sloane, Mar 11 2021
CROSSREFS
See also A006046, A335794, A335795.
Number of entries in n-th row of Pascal's triangle not divisible by 3.
(Formerly M0422)
+10
29
1, 2, 3, 2, 4, 6, 3, 6, 9, 2, 4, 6, 4, 8, 12, 6, 12, 18, 3, 6, 9, 6, 12, 18, 9, 18, 27, 2, 4, 6, 4, 8, 12, 6, 12, 18, 4, 8, 12, 8, 16, 24, 12, 24, 36, 6, 12, 18, 12, 24, 36, 18, 36, 54, 3, 6, 9, 6, 12, 18, 9, 18, 27, 6, 12, 18, 12, 24, 36, 18, 36, 54, 9, 18, 27, 18, 36, 54, 27, 54
LINKS
H. Harborth, Number of Odd Binomial Coefficients, Proc. Amer. Math. Soc. 62.1 (1977), 19-22. (Annotated scanned copy)

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