A387722 Numbers k for which A107758(k) > 2*k, but for all whose proper divisors d|k, d<k, A107758(d) <= 2*d.

6, 10, 14, 15, 21, 22, 26, 34, 38, 46, 58, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 178, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 385, 386, 394, 398, 422, 429, 446, 454, 455, 458, 466, 478, 482, 502, 514, 526, 538, 542, 554, 561, 562, 566

Offset

1,1

Comments

Not the same as the positions of 1's in A387725.

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Prog

(PARI)
A107758(n) =  { my(f = factor(n)); prod(k=1, #f~, 1+sigma(f[k, 1]^f[k, 2])); };
is_A387722(n) = if((A107758(n)<=(2*n)), 0, fordiv(n, d, if(d<n && A107758(d)>(2*d), return(0))); (1));

Crossrefs

Cf. A107758, A387725.

Setwise difference A387721 \ A387723.

Cf. also A091191, A337372, A387712.

Sequence in context: A180074 A338905 A093772 * A046400 A100660 A088709

Adjacent sequences: A387719 A387720 A387721 * A387723 A387724 A387725

Keyword

nonn

Author

Antti Karttunen, Sep 06 2025

Status

approved