A358767 - OEIS

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A358767

Numbers k with an even number of prime factors (when counted with multiplicity) in sigma(k), the sum of divisors of k.

1, 3, 5, 8, 13, 14, 15, 18, 22, 23, 24, 27, 28, 34, 36, 37, 38, 39, 40, 42, 44, 49, 50, 53, 58, 59, 61, 62, 63, 65, 66, 68, 69, 70, 73, 76, 77, 81, 82, 83, 84, 86, 89, 90, 94, 99, 100, 102, 103, 104, 110, 111, 112, 114, 115, 116, 119, 120, 121, 124, 125, 131, 132, 133, 134, 135, 139, 140, 142, 144

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..70.

Index entries for sequences where odd perfect numbers must occur, if they exist at all

Index entries for sequences related to sigma(n)

PROG

(PARI) isA358767(n) = !(bigomega(sigma(n))%2);

CROSSREFS

Positions of even terms in A058063. Positions of 1's in A358766.

Cf. A000203, A001222, A358768 (complement).