A337543 Numbers that are in A337381, but that have no proper divisor in A337381.

6, 8, 9, 14, 15, 20, 21, 35, 44, 49, 50, 52, 68, 76, 92, 110, 124, 125, 130, 148, 172, 188, 190, 212, 230, 244, 275, 286, 292, 310, 325, 338, 356, 363, 425, 429, 452, 470, 475, 494, 507, 575, 598, 627, 663, 715, 741, 759, 775, 806, 845, 847, 874, 897, 925, 969, 1001, 1023, 1058, 1075, 1083, 1131, 1173, 1175, 1183, 1209

Offset: 1

Author

Antti Karttunen, Aug 31 2020

Keywords

• nonn

Comments

Numbers k that are in A337381 [i.e., for which A003973(k) >= 2*A000203(k)], but none of whose proper divisors are in A337381.

Links

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

Crossrefs

Cf. A000203, A003961, A003973, A337381, A337383, A337541, A337542.

Cf. also A091191, A337372.

Programs

PARI

A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
A337541(n) = sumdiv(n,d,sigma(A003961(d))>=2*sigma(d));
isA337543(n) = (1==A337541(n));

Formula

{k: 1==A337541(k)}.