A007475 a(n) is the smallest positive number such that the sum of A001032(n) consecutive squares starting with a(n)^2 is a square.

1, 3, 18, 7, 1, 25, 7, 539, 25, 7, 22, 442, 225, 192, 13, 15, 26914, 244, 50, 5552, 30, 553, 7, 4493, 83342, 83, 65, 775, 3807, 64, 556, 20, 106, 132, 2277, 15, 1788, 5063, 27, 11320, 280, 358, 1805, 210, 9985, 802, 183, 71752, 10123, 16806, 94707486, 1081

Offset: 1

Author

N. J. A. Sloane, Mira Bernstein

Keywords

• nonn

Examples

			a(3)=18 because A001032(3)=11 and the sum of 11 squares 18^2 + 19^2 + ... + 28^2 = 77^2.
		

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Christopher E. Thompson, Table of n, a(n) for n = 1..10438
• Laurent Beeckmans, Squares Expressible as Sum of Consecutive Squares, Am. Math. Monthly, Volume 101, Number 5, pp. 437-442, May 1994.
• Index entries for sequences related to sums of squares

Crossrefs

Cf. A001032.

Square roots of sum are in A076215.

Extensions

Better description and more terms from Ralf Stephan, Nov 03 2002

Corrected by T. D. Noe, Aug 25 2004

Offset corrected to 1 by M. F. Hasler, Feb 02 2016