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A076674 Smallest a(n)>a(n-1) such that a(n)^2+a(n-1)^2 is a perfect square, a(1)=9. 0
9, 12, 16, 30, 40, 42, 56, 90, 120, 126, 168, 224, 360, 378, 504, 550, 1320, 1386, 1848, 1989, 2652, 2961, 3948, 5264, 8052, 9711, 12948, 17264, 24852, 31311, 41748, 53289, 71052, 94736, 130548, 145061, 146280, 153594, 163392, 170280, 173290 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sequence is infinite.

LINKS

Table of n, a(n) for n=1..41.

FORMULA

a(n)=A076671(n), n>1. [From R. J. Mathar, Sep 20 2008]

MATHEMATICA

ps[n_]:=Module[{k=n+1, n2=n^2}, While[!IntegerQ[Sqrt[n2+k^2]], k++]; k]; NestList[ ps, 9, 40] (* Harvey P. Dale, May 01 2014 *)

CROSSREFS

Cf. A076600.

Sequence in context: A166136 A120154 A084375 * A176062 A027571 A154631

Adjacent sequences:  A076671 A076672 A076673 * A076675 A076676 A076677

KEYWORD

nonn

AUTHOR

Zak Seidov, Oct 25 2002

STATUS

approved

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Last modified October 22 06:54 EDT 2019. Contains 328315 sequences. (Running on oeis4.)