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

Author

Jaroslav Krizek, Aug 04 2016

Keywords

• nonn

Comments

Even terms of A002191.

Complement of A060657 with respect to A002191.

Examples

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

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).

Crossrefs

Cf. A000203, A002191, A060657, A152678.

Programs

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