A076389 Sum of squares of numbers that cannot be written as t*n + u*(n+1) for nonnegative integers t,u.

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.

Links

Table of n, a(n) for n=1..29.

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

Adjacent sequences: A076386 A076387 A076388 * A076390 A076391 A076392

Keyword

easy,nonn

Author

Floor van Lamoen, Oct 09 2002

Status

approved