A083566 - OEIS

A083566

a(1) = 1; for n>1, a(n) = smallest odd number > a(n-1) such that a(1)*...*a(n) + 2 is a prime.

1, 3, 5, 7, 9, 15, 19, 25, 27, 53, 57, 65, 71, 87, 101, 151, 195, 247, 253, 255, 277, 289, 291, 301, 321, 355, 361, 443, 455, 461, 491, 531, 533, 541, 599, 603, 619, 635, 647, 667, 805, 817, 871, 1003, 1011, 1179, 1205, 1223, 1327, 1357, 1531, 1551, 1603, 1619

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OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..200

MATHEMATICA

a[1] = 1; a[n_] := a[n] = Block[{k = a[n - 1] + 2}, While[ !PrimeQ[k*Times @@ Table[a[i], {i, 1, n - 1}] + 2], k += 2]; k]; Table[ a[n], {n, 1, 54}]

nxt[{pr_, a_}]:=Module[{k=a+2}, While[!PrimeQ[pr k+2], k=k+2]; {pr k, k}]; NestList[nxt, {1, 1}, 60][[;; , 2]] (* Harvey P. Dale, Jul 10 2023 *)

CROSSREFS

Cf. A084723, A084724, A084725, A085013.

Sequence in context: A340559 A073674 A084722 * A109790 A290426 A211137

Adjacent sequences: A083563 A083564 A083565 * A083567 A083568 A083569