A147807 - OEIS

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A147807

Partial sums of A147810(n)=tau(n^2+1)/2.

1, 2, 4, 5, 7, 8, 11, 13, 15, 16, 18, 20, 24, 25, 27, 28, 32, 35, 37, 38, 42, 44, 48, 49, 51, 52, 56, 58, 60, 62, 66, 69, 73, 75, 77, 78, 82, 85, 87, 88, 91, 93, 99, 101, 103, 105, 113, 115, 117, 119, 121, 123, 127, 128, 132, 133, 141, 143, 145, 147, 149, 151, 155, 157 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also, number of inequivalent (i.e. q<r) integer solutions to 1/pqr = 1/p - 1/q - 1/r with p <= n; cf. A147811.`
	FORMULA	`a(n) = sum_{p = 1..n} tau(1+p^2)/2 = n + A147806(n) > n`
	PROG	`(PARI) s=0; A147807=vector(99, n, s+=numdiv(n^2+1))/2`
	CROSSREFS	`Cf. A147806, A147809-A147811.` `Sequence in context: A112886 A111040 A191324 * A022559 A049781 A174090` `Adjacent sequences: A147804 A147805 A147806 * A147808 A147809 A147810`
	KEYWORD	`easy,nonn`
	AUTHOR	`M. F. Hasler (www.univ-ag.fr/~mhasler), Dec 13 2008`

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Last modified February 14 04:48 EST 2012. Contains 205570 sequences.