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A144656 Defined by recurrence shown in Maple code below. +0
2
0, 1, 0, 1, 4, 49, 900, 24649, 944784, 48455521, 3210355600, 267186643801, 27307626948900, 3363915436531441, 491705171699154084, 84158959760104032049, 16675767262618669710400, 3787671541267275818341249, 977702867682508392324162624, 284628954669920840314598014801 (list; graph; listen)
OFFSET

0,5

COMMENT

Terms are squares; square roots give A001053.

REFERENCES

S. B. Ekhad, Problem 10356, Amer. Math. Monthly, 101 (1994), 75.

M. E. Larsen, Summa Summarum, A. K. Peters, Wellesley, MA, 2007; see p. 35.

MAPLE

a:=proc(n) option remember; local m;

if n=0 then RETURN(0); fi;

if n=1 then RETURN(1); fi;

if n=2 then RETURN(0); fi;

if n=3 then RETURN(1); fi;

m:=n-3;

RETURN((m^2+m+1)*(m+1)*a(n-1)/m+(m^2+m+1)*a(n-2)-(m+1)*a(n-3)/m);

end;

CROSSREFS

Sequence in context: A053769 A086094 A055793 this_sequence A121275 A029991 A129419

Adjacent sequences: A144653 A144654 A144655 this_sequence A144657 A144658 A144659

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Jan 30 2009

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.


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