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A076462 Sum of squares of numbers that can be written as t*n + u*(n+1) for nonnegative integers t,u in exactly three ways. 1
41, 1471, 12938, 62870, 218555, 611821, 1471316, 3161388, 6227565, 11448635, 19895326, 32995586, 52606463, 81092585, 121411240, 177204056, 252895281, 353796663, 486218930, 657589870, 876579011, 1153228901, 1499092988, 1927380100, 2453105525, 3093248691 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
REFERENCES
Fred. Schuh, Vragen betreffende een onbepaalde vergelijking, Nieuw Tijdschrift voor Wiskunde, 52 (1964-1965) 193-198.
LINKS
FORMULA
a(n) = n*(n+1)*(55*n^4+74*n^3+6*n^2-13*n+1)/6.
G.f.: x*(41+1184*x+3502*x^2+1760*x^3+113*x^4)/(1-x)^7.
MAPLE
seq(1/6*n*(n+1)*(55*n^4+74*n^3+6*n^2-13*n+1), n=1..30);
MATHEMATICA
CoefficientList[Series[(41 + 1184 x + 3502 x^2 + 1760 x^3 + 113 x^4)/(1 - x)^7, {x, 0, 50}], x] (* Vincenzo Librandi, Dec 30 2013 *)
PROG
(Magma) [n*(n+1)*(55*n^4+74*n^3+6*n^2-13*n+1)/6: n in [1..50]]; // Vincenzo Librandi, Dec 30 2013
CROSSREFS
Sequence in context: A094455 A239251 A197527 * A163050 A305863 A180667
KEYWORD
nonn,easy
AUTHOR
Floor van Lamoen, Oct 13 2002
STATUS
approved

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Last modified February 25 00:32 EST 2024. Contains 370308 sequences. (Running on oeis4.)