A059775 - OEIS

A059775

From solution to a counting problem.

0, 24, 120, 360, 824, 1664, 2992, 5000, 7848, 11808, 17024, 23888, 32576, 43432, 56816, 73136, 92616, 115872, 143104, 174928, 211808, 254312, 302680, 357832, 420136, 490232, 568664, 656360, 753496, 861376, 980232, 1111016, 1254504

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..32.

Emeric Deutsch, Murray S. Klamkin and Denis Constales, Solution to Problem 10540: Counting the Solutions, Amer. Math. Monthly, 108 (Feb. 2001), 172-173.

MAPLE

[seq(n*(n-1)*(n^2-n-1) + 4*add(floor(n/k^2)*phi(k), k=2..floor(sqrt(n))) - 2*add(floor(n/k)^2*phi(k), k=2..n), n=2..30)];

CROSSREFS

Sequence in context: A229567 A069074 A360389 * A372497 A052762 A217056

Adjacent sequences: A059772 A059773 A059774 * A059776 A059777 A059778

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 21 2001

STATUS

approved