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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 * A192842 A012813 A031612

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 August 18 14:09 EDT 2017. Contains 290720 sequences.