A335882 Numbers k for which A331410(k) = 2.

5, 9, 10, 11, 13, 18, 20, 21, 22, 23, 26, 36, 40, 42, 44, 46, 47, 49, 52, 61, 72, 80, 84, 88, 92, 93, 94, 98, 104, 122, 144, 160, 168, 176, 184, 186, 188, 191, 196, 208, 217, 223, 244, 288, 320, 336, 352, 368, 372, 376, 381, 382, 383, 392, 416, 434, 446, 488, 576, 640, 672, 704, 736, 744, 752, 762, 764, 766, 784, 832, 868, 889, 892, 961

Offset

1,1

Comments

Numbers k such that A000265(k) is either in A144482 or in A335874.

Each term is either of the form A335874(n)*2^k, for some n >= 2, and k >= 0, or a product of two terms of A335431, whether distinct or not.

Links

Antti Karttunen, Table of n, a(n) for n = 1..600

Prog

(PARI)
A000265(n) = (n>>valuation(n, 2));
isA000668(n) = (isprime(n)&&!bitand(n, 1+n));
isA144482(n) = ((2==bigomega(n))&&isA000668(vecmin(factor(n)[, 1]))&&isA000668(vecmax(factor(n)[, 1])));
isA335874(n) = ((n>2)&&isprime(n)&&isA000668(A000265(1+n)));
isA335882(n) = (isA335874(A000265(n))||isA144482(A000265(n)));

Crossrefs

Row 2 of A335430.

Cf. A331410, A335431, A335874 (after its initial 2, gives the primes in this sequence), A144482 (odd semiprimes in this sequence).

Cf. also A334102.

Sequence in context: A094695 A268412 A043682 * A111102 A139456 A195684

Adjacent sequences: A335879 A335880 A335881 * A335883 A335884 A335885

Keyword

nonn,changed

Author

Antti Karttunen, Jun 28 2020

Status

approved