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A071133 Squares which repeat with at least two full periods when written in base 7. 1
16, 400, 900, 1600, 29584, 70627216, 394618225, 2214643600, 4982948100, 8858574400, 16052636601, 64210546404, 169556179984, 727092173809, 1120597967889, 2908368695236, 6543829564281, 6703226505481, 79822717134736, 407103419654416, 12766762698010000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..39 (terms < 7^29)

EXAMPLE

19865^2 = 394618225 = 12531|12531|1 in base 7.

411772^2 = 169556179984 = 1515152|1515152 in base 7.

MATHEMATICA

psq[b_, nd_] := Block[{sq={}, r, x}, Do[r = Mod[nd, p]; Do[x = (b^( Floor[nd/p] p) - 1)/(b^p - 1) t  b^r + Floor[t/b^(p - r)]; If[ IntegerQ@ Sqrt@ x, AppendTo[ sq, x]], {t, b^(p - 1), b^p - 1}], {p, nd/2}]; sq]; Union @@ (psq[7, #] & /@ Range[12]) (* Giovanni Resta, Aug 01 2018 *)

CROSSREFS

Cf. A071128 (base 2) - A071135 (base 9), A069919 (base 10).

Sequence in context: A284854 A269412 A269643 * A186854 A035021 A300469

Adjacent sequences:  A071130 A071131 A071132 * A071134 A071135 A071136

KEYWORD

base,nonn

AUTHOR

Erich Friedman, May 28 2002

EXTENSIONS

a(17)-a(21) from Giovanni Resta, Aug 01 2018

STATUS

approved

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Last modified August 22 00:43 EDT 2019. Contains 326169 sequences. (Running on oeis4.)