A062091 a(1) = 2, a(n)= smallest even number which does not divide the product of all previous terms.

2, 4, 6, 10, 14, 18, 22, 26, 34, 38, 46, 50, 58, 62, 74, 82, 86, 94, 98, 106, 118, 122, 134, 142, 146, 158, 162, 166, 178, 194, 202, 206, 214, 218, 226, 242, 254, 262, 274, 278, 298, 302, 314, 326, 334, 338, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454

Offset

1,1

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Formula

2 and 4 together with numbers of the form 2*{p^(2^k)} where p is an odd prime and k is a nonnegative integer. [Corrected by Peter Munn, Nov 03 2020]

Example

After 10 the next term in the sequence is 14 (not 12) as 12 = 2*6 divides the product of all the previous terms.

Mathematica

Block[{a = {2}, k = 4, P = 1}, Do[Set[P, P*a[[-1]]]; While[Mod[P, k] == 0, k += 2]; AppendTo[a, k], {i, 2, 56}]; a] (* Michael De Vlieger, Nov 04 2020 *)

Crossrefs

Cf. A026477, A062090.

Sequence in context: A288526 A139544 A356959 * A100143 A234941 A303744

Adjacent sequences: A062088 A062089 A062090 * A062092 A062093 A062094

Keyword

nonn

Author

Amarnath Murthy, Jun 16 2001

Extensions

More terms from Dean Hickerson, Jul 10 2001

Status

approved