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A076389
Sum of squares of numbers that cannot be written as t*n + u*(n+1) for nonnegative integers t,u.
7
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
OFFSET
1,3
REFERENCES
Fred. Schuh, Vragen betreffende een onbepaalde vergelijking, Nieuw Tijdschrift voor Wiskunde, 52 (1964-1965) 193-198.
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
MAPLE
seq(n^2*(n^2-1)*(n^2-n-1)/12, n=1..40);
CROSSREFS
Cf. A002417.
Sequence in context: A042754 A215192 A244836 * A342896 A189410 A210101
KEYWORD
easy,nonn
AUTHOR
Floor van Lamoen, Oct 09 2002
STATUS
approved