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

Author

Floor van Lamoen, Oct 09 2002

Keywords

• easy
• nonn

References

• Fred. Schuh, Vragen betreffende een onbepaalde vergelijking, Nieuw Tijdschrift voor Wiskunde, 52 (1964-1965) 193-198.

Links

• Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).

Crossrefs

Cf. A002417, A076460-A076465.

Programs

Maple

seq(n^2*(n^2-1)*(n^2-n-1)/12,n=1..40);

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