A336919 Numbers k such that A000005(k) does not divide A003973(k); numbers k for which A336839(k) > 1.

4, 9, 16, 18, 20, 32, 36, 44, 45, 48, 49, 64, 68, 72, 80, 81, 90, 98, 99, 100, 112, 116, 124, 144, 153, 160, 162, 164, 169, 176, 180, 192, 196, 198, 208, 220, 225, 236, 240, 244, 245, 252, 256, 261, 279, 284, 288, 292, 304, 306, 320, 324, 336, 338, 340, 352, 356, 360, 361, 369, 392, 396, 400, 404, 405, 428, 432, 441

Offset: 1

Author

Antti Karttunen, Aug 12 2020

Keywords

• nonn

Comments

Numbers k such that A003961(k) is not in A003601, but in A049642.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000
• Index entries for sequences computed from indices in prime factorization

Crossrefs

Cf. A000005, A003601, A003961, A003973, A049642, A336839.

Cf. A336918 (complement).

Programs

PARI

A003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
isA336919(n) = !!(sigma(A003961(n))%numdiv(n));