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 A076464 Sum of squares of numbers that can be written as t*n + u*(n+1) for nonnegative integers t,u in exactly five ways. 2
 145, 4567, 38570, 183670, 630755, 1751365, 4187092, 8957100, 17583765, 32236435, 55893310, 92521442, 147274855, 226710785, 339024040, 494299480, 704782617, 985168335, 1352907730, 1828533070, 2436000875, 3203053117, 4161596540, 5348100100, 6804010525 (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 Vincenzo Librandi, Table of n, a(n) for n = 1..1000 FORMULA a(n) = n*(n+1)*(151*n^4+242*n^3+66*n^2-25*n+1)/6. G.f.: x*(145+3552*x+9646*x^2+4512*x^3+265*x^4)/(1-x)^7. MAPLE seq(1/6*n*(n+1)*(151*n^4+242*n^3+66*n^2-25*n+1), n=1..30); MATHEMATICA CoefficientList[Series[(145 + 3552 x + 9646 x^2 + 4512 x^3 + 265 x^4)/(1 - x)^7, {x, 0, 50}], x] (* Vincenzo Librandi, Dec 30 2013 *) PROG (Magma) [n*(n+1)*(151*n^4+242*n^3+66*n^2-25*n+1)/6: n in [1..50]]; // Vincenzo Librandi, Dec 30 2013 CROSSREFS Cf. A076389, A076460-A076465. Sequence in context: A232151 A264284 A008377 * A018232 A192842 A012813 Adjacent sequences: A076461 A076462 A076463 * A076465 A076466 A076467 KEYWORD easy,nonn AUTHOR Floor van Lamoen, Oct 13 2002 EXTENSIONS More terms from Vincenzo Librandi, Dec 30 2013 STATUS approved

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Last modified May 22 20:45 EDT 2024. Contains 372758 sequences. (Running on oeis4.)