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A076389
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Sum of squares of numbers that cannot be written as t*n + u*(n+1) for nonnegative integers t,u.
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7
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0, 1, 30, 220, 950, 3045, 8036, 18480, 38340, 73425, 131890, 224796, 366730, 576485, 877800, 1300160, 1879656, 2659905, 3693030, 5040700, 6775230, 8980741, 11754380, 15207600, 19467500, 24678225, 31002426, 38622780, 47743570
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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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
| n^2*(n^2-1)*(n^2-n-1)/12. G.f.:(1+23*x+31*x^2+5*x^3)*x^2/(1-x)^7
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MAPLE
| seq(n^2*(n^2-1)*(n^2-n-1)/12, n=1..40);
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CROSSREFS
| Cf. A002417.
Sequence in context: A178672 A061661 A042754 * A189410 A156372 A064241
Adjacent sequences: A076386 A076387 A076388 * A076390 A076391 A076392
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KEYWORD
| easy,nonn
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AUTHOR
| Floor van Lamoen (fvlamoen(AT)hotmail.com), Oct 09 2002
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