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A073351
n^2(n+1)(2n+1)^2(7n+1)/36.
0
0, 4, 125, 1078, 5220, 18150, 50869, 122500, 263568, 519840, 956725, 1664234, 2762500, 4407858, 6799485, 10186600, 14876224, 21241500, 29730573, 40876030, 55304900, 73749214, 97057125, 126204588, 162307600, 206635000, 260621829
OFFSET
0,2
REFERENCES
Mentioned in a problem on p. 334 of Two-Year College Math. Jnl., Vol. 25, 1994.
FORMULA
a(n)=sum(i=1, n, i^2)*sum(i=n+1, 2*n, i^2).
G.f.: x(4+97x+287x^2+159x^3+13x^4)/(1-x)^7.
CROSSREFS
Cf. A007750.
Sequence in context: A209040 A068891 A337245 * A195797 A354549 A286017
KEYWORD
nonn,easy
AUTHOR
Michael Somos, Jul 27 2002
STATUS
approved