id:A086988 - OEIS Search Results

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Sum of odd indexed divisors of n.

+0
2

1, 1, 1, 5, 1, 4, 1, 5, 10, 6, 1, 10, 1, 8, 6, 21, 1, 13, 1, 15, 8, 12, 1, 22, 26, 14, 10, 19, 1, 25, 1, 21, 12, 18, 8, 58, 1, 20, 14, 33, 1, 32, 1, 27, 21, 24, 1, 46, 50, 31, 18, 31, 1, 40, 12, 41, 20, 30, 1, 64, 1, 32, 29, 85, 14, 48, 1, 39, 24, 51, 1, 73, 1, 38, 31, 43, 12, 56, 1, 69 (list; graph; listen)

	OFFSET	`1,4`
	COMMENT	`a(p)=1 iff p is prime or p=1`
	EXAMPLE	`10 has divisors 1,2,5 and 10. The even indices yield 1 and 15, so a(10)=6`
	PROGRAM	`(PARI) for (n=1, 100, s=0; c=-1; fordiv(i=n, i, c++; if (c%2==0, s+=i)); print1(", "s))`
	CROSSREFS	`Cf. A086989.` `Sequence in context: A127551 A023138 A108170 this_sequence A010132 A033988 A019977` `Adjacent sequences: A086985 A086986 A086987 this_sequence A086989 A086990 A086991`
	KEYWORD	`nonn`
	AUTHOR	`Jon Perry (perry(AT)globalnet.co.uk), Jul 27 2003`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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