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A121869 Monthly Problem 10791, first expression. 1
-1, 1, 0, -5, -15, 104, 1827, 7893, -207000, -5646249, -47897675, 1479282600, 74711288407, 1396956334921, -21032523700672, -2719998717430365, -104158663871982343, -715846242343471272, 189941380201812700699, 14820744271258596866013, 507768838531742620183176 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..20.

A. Fekete and G. Martin, Problem 10791: Squared Series Yielding Integers, Amer. Math. Monthly, 108 (No. 2, 2001), 177-178.

FORMULA

a(n) = A024429(n)^2 - A024430(n)^2.

CROSSREFS

Cf. A121870, A024429, A024430, A121867, A121868.

Sequence in context: A134135 A292279 A268565 * A118412 A068622 A080449

Adjacent sequences:  A121866 A121867 A121868 * A121870 A121871 A121872

KEYWORD

sign

AUTHOR

N. J. A. Sloane, Sep 05 2006

STATUS

approved

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Last modified April 20 17:54 EDT 2019. Contains 322310 sequences. (Running on oeis4.)