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A061369 a(n) = smallest square in the arithmetic progression {nk+1 : k >= 0}. 0
4, 9, 4, 9, 16, 25, 36, 9, 64, 81, 100, 25, 144, 169, 16, 49, 256, 289, 324, 81, 64, 441, 484, 25, 576, 625, 676, 169, 784, 121, 900, 225, 100, 1089, 36, 289, 1296, 1369, 196, 81, 1600, 169, 1764, 441, 361, 2025, 2116, 49, 2304, 2401, 256, 625, 2704, 2809, 441 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..55.

FORMULA

a(n)=Min{x^2 : x^2=nk+1}

EXAMPLE

Each square q appears in several progressions, i.e. in A000005(q-1) cases. Not necessarily as a first square. E.g. q=81 is minimal in {10k+1},{20k+1},{40k+1},{80k+1}, while not minimal in {3k+1} and 5 other progressions. In {16k+1} 49 comes before 81.

CROSSREFS

Sequence in context: A061767 A131016 A204996 * A291645 A340769 A088377

Adjacent sequences:  A061366 A061367 A061368 * A061370 A061371 A061372

KEYWORD

nonn

AUTHOR

Labos Elemer, Jun 08 2001

STATUS

approved

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Last modified August 1 08:54 EDT 2021. Contains 346385 sequences. (Running on oeis4.)