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A144065
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Values of n such that the expression sqrt(4!*(n+1) + 1) yields an integer.
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3
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0, 1, 4, 6, 11, 14, 21, 25, 34, 39, 50, 56, 69, 76, 91, 99, 116, 125, 144, 154, 175, 186, 209, 221, 246, 259, 286, 300
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| a(n)=3a(n-2)-3a(n-4)+a(n-6) [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Jan 21 2009]
a(n) = -3/16+1/8*(-1)^n*n+3/16*(-1)^n+3/8*n^2+9/8*n [From Alexander R. Povolotsky (pevnev(AT)juno.com), Jan 27 2009]
a(n) = A001318(n+1)-1. [From Peter Bala (pbala(AT)talktalk.net), Mar 22 2009]
G.f.: x*(1+3*x-x^3)/((1+x)^2*(1-x)^3) [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Aug 31 2009]
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PROG
| (PARI) j=[]; for(n=0, 300, if((floor(sqrt(4!*(n+1) + 1))) == ceil(sqrt(4!*(n+1) + 1)), j=concat(j, n))); j
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CROSSREFS
| Cf. A075889, A038179, A007310.
Sequence in context: A096833 A153357 A002732 * A036831 A084263 A060180
Adjacent sequences: A144062 A144063 A144064 * A144066 A144067 A144068
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KEYWORD
| nonn
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AUTHOR
| Alexander R. Povolotsky (pevnev(AT)juno.com), Sep 09 2008
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