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A057721 n^4 + 3*n^2 + 1. 9
1, 5, 29, 109, 305, 701, 1405, 2549, 4289, 6805, 10301, 15005, 21169, 29069, 39005, 51301, 66305, 84389, 105949, 131405, 161201, 195805, 235709, 281429, 333505, 392501, 459005, 533629, 617009, 709805, 812701, 926405, 1051649 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Longest possible side c of a triangle with integer sides a<=b<c and inradius n. Triangle has sides (n^2+2,n^4+2n^2+1,n^4+3n^2+1). Proved by Joseph Myers, Jun 11 2006.

LINKS

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

FORMULA

a(n) = Denominator of Integral(sin(n*x)/(exp((n^2+1)*x)),x=0..infinity). [Francesco Daddi, Jul 07 2013]

MAPLE

with(combinat, fibonacci):seq(fibonacci(5, i), i=0..32); - Zerinvary Lajos, Dec 01 2006

MATHEMATICA

Table[Fibonacci[5, i], {i, 0, 40}]; ..and/or..f[n_]:=n^4+3n^2+1; Array[f, 40, 0] (* Vladimir Joseph Stephan Orlovsky, Nov 03 2009 *)

PROG

(Sage) [lucas_number1(5, n, -1) for n in xrange(0, 33)] # Zerinvary Lajos, May 16 2009

CROSSREFS

See A120062 for sequences related to integer-sided triangles with integer inradius n.

Cf. A120062 [triangles with integer inradius], A120063 [minimum of their longest sides].

Sequence in context: A097344 A153076 A034700 * A085151 A119494 A153077

Adjacent sequences:  A057718 A057719 A057720 * A057722 A057723 A057724

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Oct 27 2000

STATUS

approved

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Last modified April 24 15:35 EDT 2014. Contains 240985 sequences.