A275671 Even values produced by the sigma function A000203, in increasing order.

4, 6, 8, 12, 14, 18, 20, 24, 28, 30, 32, 36, 38, 40, 42, 44, 48, 54, 56, 60, 62, 68, 72, 74, 78, 80, 84, 90, 96, 98, 102, 104, 108, 110, 112, 114, 120, 124, 126, 128, 132, 138, 140, 144, 150, 152, 156, 158, 160, 162, 164, 168, 174, 176, 180, 182, 186, 192, 194

Offset

1,1

Comments

Even terms of A002191.

Complement of A060657 with respect to A002191.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).

Example

8 is in the sequence because sigma(7) = 8 and it is an even number.

Prog

(Magma) Set(Sort([SumOfDivisors(n): n in[1..1000] | not IsOdd(SumOfDivisors(n)) and SumOfDivisors(n) le 1000]));
(PARI) is(k) = !(k % 2) && invsigmaNum(k) > 0; \\ Amiram Eldar, Dec 26 2024, using Max Alekseyev's invphi.gp

Crossrefs

Cf. A000203, A002191, A060657, A152678.

Sequence in context: A053579 A074121 A175088 * A370745 A055670 A141096

Adjacent sequences: A275668 A275669 A275670 * A275672 A275673 A275674

Keyword

nonn

Author

Jaroslav Krizek, Aug 04 2016

Status

approved