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. (Formerly M3043)

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

1,2

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

Example

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

Crossrefs

Cf. A001032.

Square roots of sum are in A076215.

Sequence in context: A120647 A131635 A324554 * A324889 A281791 A281722

Adjacent sequences: A007472 A007473 A007474 * A007476 A007477 A007478

Keyword

nonn

Author

N. J. A. Sloane, Mira Bernstein

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

Status

approved