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A074061 Positive integers n such that 24*n^2-23 is a square. 0
1, 4, 6, 39, 59, 386, 584, 3821, 5781, 37824, 57226, 374419, 566479, 3706366, 5607564, 36689241, 55509161, 363186044, 549484046, 3595171199, 5439331299, 35588525946, 53843828944, 352290088261, 532998958141, 3487312356664 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

LINKS

Index entries for two-way infinite sequences

K. S. Brown, Numbers Expressible as (a^2-1)(b^2-1)

FORMULA

a(2n-1) = round((1/2)*(1-(1/2)/sqrt(6))*(sqrt(2)+sqrt(3))^(2n)); a(2n)=round(c*(sqrt(2)+sqrt(3))^(2n+1)) with c =0.191357750597... - Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 22 2002

G.f.: (1-x)(1+5x+x^2)/(1-10x^2+x^4). a(n)=10a(n-2)-a(n-4)=a(-1-n).

PROG

(PARI) a(n)=if(n<0, a(-1-n), polcoeff((1-x)*(1+5*x+x^2)/(1-10*x^2+x^4)+x*O(x^n), n))

CROSSREFS

Sequence in context: A092765 A056315 A103234 * A125081 A175349 A023644

Adjacent sequences:  A074058 A074059 A074060 * A074062 A074063 A074064

KEYWORD

nonn

AUTHOR

Michael Somos, Aug 19, 2002

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Last modified February 14 16:59 EST 2012. Contains 205636 sequences.