

A002021


Pile of coconuts problem: (n1)(n^n  1), n even; n^n  n + 1, n odd.
(Formerly M3114 N1262)


5



1, 3, 25, 765, 3121, 233275, 823537, 117440505, 387420481, 89999999991, 285311670601, 98077104930805, 302875106592241, 144456088732254195, 437893890380859361, 276701161105643274225, 827240261886336764161, 668888937280041138782191, 1978419655660313589123961
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OFFSET

1,2


REFERENCES

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

T. D. Noe, Table of n, a(n) for n = 1..100
Santo D'Agostino, “The Coconut Problem”; Updated With Solution, May 2011.
R. S. Underwood and Robert E. Moritz, Problem 3242, Amer. Math. Monthly, 35 (1928), 4748.
Ben Ames Williams, Coconuts Problem
R. G. Wilson, V, Letter to N. J. A. Sloane, Oct. 1993


FORMULA

E.g.f.: (1x)*exp(x)(W(x)+2)*(2*W(x)+1)/(2*(1+W(x))^3)W(x)/(2*(1+W(x))^3) where W is the Lambert W function.  Robert Israel, Aug 26 2016


MAPLE

seq(`if`(n::even, (n1)*(n^n  1), n^nn+1), n=1..30); # Robert Israel, Aug 26 2016


MATHEMATICA

Table[If[EvenQ[n], (n1)(n^n1), n^nn+1], {n, 30}] (* Harvey P. Dale, Apr 21 2012 *)


CROSSREFS

Cf. A002022, A006091.
Sequence in context: A127231 A062411 A136516 * A322063 A306792 A012764
Adjacent sequences: A002018 A002019 A002020 * A002022 A002023 A002024


KEYWORD

easy,nonn,nice


AUTHOR

N. J. A. Sloane


EXTENSIONS

More terms from Harvey P. Dale, Apr 21 2012


STATUS

approved



