A261996 The first of twenty-one consecutive positive integers the sum of the squares of which is equal to the sum of the squares of four consecutive positive integers.
8, 44, 128, 788, 2024, 5948, 15176, 87764, 223712, 655316, 1670312, 9654332, 24607376, 72079892, 183720224, 1061889836, 2706588728, 7928133884, 20207555408, 116798228708, 297700153784, 872022648428, 2222647375736, 12846743269124, 32744310328592
Offset: 1
Examples
8 is in the sequence because 8^2 + ... + 28^2 = 7574 = 42^2 + ... + 45^2.
Links
- Colin Barker, Table of n, a(n) for n = 1..1000
- Index entries for linear recurrences with constant coefficients, signature (1,0,0,110,-110,0,0,-1,1).
Programs
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PARI
Vec(4*x*(x^8+3*x^7+3*x^6+9*x^5-89*x^4-165*x^3-21*x^2-9*x-2)/((x-1)*(x^8-110*x^4+1)) + O(x^40))
Formula
G.f.: 4*x*(x^8+3*x^7+3*x^6+9*x^5-89*x^4-165*x^3-21*x^2-9*x-2) / ((x-1)*(x^8-110*x^4+1)).
Comments