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A076461
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Sum of squares of numbers that can be written as t*n + u*(n+1) for nonnegative integers t,u in exactly two ways.
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1
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13, 571, 5306, 26470, 93455, 264313, 640276, 1383276, 2736465, 5047735, 8796238, 14621906, 23357971, 36066485, 54076840, 79027288, 112909461, 158115891, 217490530, 294382270, 392701463, 516979441, 672431036, 865020100
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| Fred. Schuh, Vragen betreffende een onbepaalde vergelijking, Nieuw Tijdschrift voor Wiskunde, 52 (1964-1965) 193-198.
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FORMULA
| 1/6*n*(n+1)*(25*n^4+26*n^3-6*n^2-7*n+1). G.f.: x*(61*x^4+864*x^3+1582*x^2+480*x+13)/((1+x)*(1-x)^7).
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MAPLE
| seq(1/6*n*(n+1)*(25*n^4+26*n^3-6*n^2-7*n+1), n=1..30);
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CROSSREFS
| Cf. A076389, A076460-A076465.
Sequence in context: A203360 A050286 A096761 * A168601 A142210 A109875
Adjacent sequences: A076458 A076459 A076460 * A076462 A076463 A076464
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KEYWORD
| easy,nonn
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AUTHOR
| Floor van Lamoen (fvlamoen(AT)hotmail.com), Oct 13 2002
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