A341615 Numbers k for which sigma(k) < 2k < A003961(k).

4, 8, 9, 10, 14, 15, 16, 21, 27, 32, 35, 39, 44, 45, 49, 50, 52, 57, 63, 64, 68, 69, 75, 76, 81, 91, 92, 98, 99, 105, 110, 116, 117, 124, 125, 128, 130, 135, 136, 147, 148, 152, 153, 154, 164, 165, 170, 171, 172, 175, 182, 184, 188, 189, 190, 195, 207, 212, 225, 230, 231, 232, 236, 238, 242, 243, 244, 245, 248, 250, 255, 256

Offset

1,1

Comments

Deficient numbers in A246282.

Not all odd terms are in A337372.

Links

Table of n, a(n) for n=1..72.

Prog

(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
isA341615(n) = A341613(n);

Crossrefs

Intersection of A005100 and A246282. Subsequence of A341614.

Cf. A341613 (characteristic function).

Cf. A000203, A003961, A252748, A286385, A326057, A326134, A337372.

Sequence in context: A210998 A205524 A125493 * A164923 A141608 A367768

Adjacent sequences: A341612 A341613 A341614 * A341616 A341617 A341618

Keyword

nonn

Author

Antti Karttunen, Feb 22 2021

Status

approved