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

Author

Colin Barker, Sep 06 2015

Keywords

• nonn
• easy

Comments

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

Examples

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

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).

Crossrefs

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

Programs

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))

Formula

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