A331464 - OEIS

A331464

Numbers k such that k and k + 1 are both binary Smith numbers (A278909).

1369, 1370, 1390, 1630, 1929, 2525, 2526, 2930, 3013, 3309, 3501, 3502, 3686, 3805, 3953, 3954, 4043, 4726, 4854, 5620, 5621, 5917, 6068, 6682, 6774, 6838, 7025, 7089, 7115, 7671, 7738, 7786, 8075, 9654, 9915, 10366, 10982, 11166, 11227, 11506, 11673, 11740, 11763

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

1369 is in the sequence since both 1369 and 1369 + 1 = 1370 are binary Smith numbers.

MATHEMATICA

binWt[n_] := Total @ IntegerDigits[n, 2]; binSmithQ[n_] := CompositeQ[n] && Plus @@ (Last@# * binWt[ First@# ] & /@ FactorInteger[n]) == binWt[n]; seq = {}; isSmith1 = binSmithQ[1]; Do[isSmith2 = binSmithQ[n]; If[isSmith1 && isSmith2, AppendTo[seq, n-1]]; isSmith1 = isSmith2, {n, 2, 12000}]; seq

CROSSREFS

Cf. A006753, A050219, A050220, A278909, A331463, A331465.

Sequence in context: A231268 A192823 A221932 * A167724 A156574 A145697

Adjacent sequences: A331461 A331462 A331463 * A331465 A331466 A331467

KEYWORD

nonn,base

AUTHOR

Amiram Eldar, Jan 17 2020

STATUS

approved