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A069019 Smallest square k > 1 such that n*k + 1 is also a square or 0 if no such term exists, i.e., when n is a square. 0
0, 4, 16, 0, 16, 4, 9, 36, 0, 36, 9, 4, 32400, 16, 64, 0, 64, 16, 1521, 4, 144, 1764, 25, 100, 0, 100, 25, 576, 3312400, 4, 74529, 9, 16, 36, 144, 0, 144, 36, 16, 9, 102400, 4, 281961, 900, 576, 12873744, 49, 196, 0, 196, 49, 8100, 82810000, 4356, 144, 4, 400 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Terms from Robert G. Wilson v.

LINKS

Table of n, a(n) for n=0..56.

MATHEMATICA

Do[k = 0; If[ !IntegerQ[ Sqrt[n]], k = 2; While[ !IntegerQ[ Sqrt[n*k^2 + 1]], k++ ]]; Print[k^2], {n, 1, 60}] (* Robert G. Wilson v *)

CROSSREFS

Cf. A069018.

Sequence in context: A330315 A061849 A052107 * A188249 A228559 A165410

Adjacent sequences:  A069016 A069017 A069018 * A069020 A069021 A069022

KEYWORD

nonn

AUTHOR

Robert G. Wilson v and Amarnath Murthy, Apr 02 2002

STATUS

approved

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Last modified December 7 15:24 EST 2021. Contains 349581 sequences. (Running on oeis4.)