A261935 The first of seventeen consecutive positive integers the sum of the squares of which is equal to the sum of the squares of two consecutive positive integers.

5, 23, 933, 2175, 65849, 152771, 4609041, 10692339, 322567565, 748311503, 22575121053, 52371113415, 1579935906689, 3665229628091, 110572938347721, 256513702853499, 7738525748434325, 17952293970117383, 541586229452055573, 1256404064205363855

Offset

1,1

Comments

For the first of the corresponding two consecutive positive integers, see A261933.

Links

Colin Barker, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,70,-70,-1,1).

Formula

G.f.: x*(21*x^4+18*x^3-560*x^2-18*x-5) / ((x-1)*(x^4-70*x^2+1)).

Example

5 is in the sequence because 5^2 + 6^2 + ... + 21^2 = 40^2 + 41^2.

Prog

(PARI) Vec(x*(21*x^4+18*x^3-560*x^2-18*x-5)/((x-1)*(x^4-70*x^2+1)) + O(x^40))

Crossrefs

Cf. A001652, A031138, A261932, A261933, A261934.

Sequence in context: A003487 A361402 A055490 * A299360 A002811 A177134

Adjacent sequences: A261932 A261933 A261934 * A261936 A261937 A261938

Keyword

nonn,easy

Author

Colin Barker, Sep 06 2015

Status

approved