id:A057934 - OEIS Search Results

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Number of prime factors of 10^n + 1 (counted with multiplicity).

+0
12

1, 1, 3, 2, 2, 2, 2, 2, 5, 3, 5, 3, 3, 4, 7, 5, 4, 3, 2, 4, 8, 4, 5, 3, 5, 3, 7, 4, 3, 7, 2, 4, 9, 4, 5, 6, 4, 3, 10, 4, 3, 7, 4, 4, 12, 4, 4, 9, 4, 7, 8, 4, 2, 6, 10, 5, 6, 5, 4, 6, 3, 3, 12, 3, 6, 8, 2, 4, 10, 11, 3, 5, 4, 7, 11, 6, 12, 7, 4, 9, 11, 3, 7, 8, 8, 3, 8, 4, 4, 11, 6, 4, 8, 4, 6, 8, 4, 5, 13 (list; graph; listen)

	OFFSET	`1,3`
	COMMENT	`2^(a(2n)-1)-1 predicts the number of pair_solutions of even length L for AB = A^2 + B^2. For instance with length 18 we have 10^18 + 1 = 101.9901.999999000001 or 3 divisors F which when put into the Mersenne formula 2^(F-1)-1 yields 3 pairs (see reference 'Puzzle 104' for details).`
	LINKS	`C. Rivera, Puzzle 104` `S. S. Wagstaff, Jr., Main Tables from the Cunningham Project.` `S. S. Wagstaff, Jr., The Cunningham Project`
	FORMULA	`a(n) = A057951(2n) - A057951(n) - T. D. Noe (noe(AT)sspectra.com), Jun 19 2003`
	CROSSREFS	`Cf. A003021, A001271, A046053, A057935-A057941, A054992, A001562.` `Cf. A057951.` `Sequence in context: A058758 A104223 A119704 this_sequence A122396 A037199 A145376` `Adjacent sequences: A057931 A057932 A057933 this_sequence A057935 A057936 A057937`
	KEYWORD	`nonn`
	AUTHOR	`Patrick De Geest (pdg(AT)worldofnumbers.com), Oct 15 2000.`

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.

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