id:A000925 - OEIS Search Results

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Number of ordered ways of writing n as a sum of 2 squares of nonnegative integers.

+0
3

1, 2, 1, 0, 2, 2, 0, 0, 1, 2, 2, 0, 0, 2, 0, 0, 2, 2, 1, 0, 2, 0, 0, 0, 0, 4, 2, 0, 0, 2, 0, 0, 1, 0, 2, 0, 2, 2, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 0, 2, 3, 0, 2, 2, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 2, 4, 0, 0, 2, 0, 0, 0, 1, 2, 2, 0, 0, 0, 0, 0, 2, 2, 2, 0, 0, 4, 0, 0, 0, 2, 2, 0, 0, 0, 0, 0, 0, 2, 1, 0, 4 (list; graph; listen)

	OFFSET	`0,2`
	REFERENCES	`A. Das and A. C. Melissinos, Quantum Mechanics: A Modern Introduction, Gordon and Breach, 1986, p. 47.` `E. Grosswald, Representations of Integers as Sums of Squares. Springer-Verlag, NY, 1985.`
	LINKS	`T. D. Noe, Table of n, a(n) for n=0..10000` `Index entries for sequences related to sums of squares`
	FORMULA	`Coefficient of q^k in (1/4)*(1 + theta_3(0, q))^2.` `a(A001481(n))>0; a(A022544(n))=0. - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 20 2003`
	PROGRAM	`(PARI) a(n)=sum(i=0, n, sum(j=0, n, if(i^2+j^2-n, 0, 1)))`
	CROSSREFS	`Adjacent sequences: A000922 A000923 A000924 this_sequence A000926 A000927 A000928` `Sequence in context: A025253 A112178 A134663 this_sequence A003985 A157237 A065676`
	KEYWORD	`nonn,nice`
	AUTHOR	`Jacques Haubrich (jhaubrich(AT)freeler.nl)`

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Last modified November 8 20:39 EST 2009. Contains 166234 sequences.

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