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URL: https://oeis.org/A071130

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A071130
Squares which repeat with at least two full periods when written in base 4.
1
6241, 378225, 672400, 1320201, 28121809, 302794801, 386554921, 1211179204, 7681646025, 73073443041, 79698371481, 91424593225, 120297291921, 292293772164, 318793485924, 657660987369, 1521820771641, 18145972716481, 72583890865924, 163313754448329
OFFSET
1,1
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..80 (terms < 4^38)
EXAMPLE
79^2 = 6241 = 120|120|1 in base 4.
615^2 = 378225 = 11301|11301 in base 4.
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[4, #] & /@ Range[16]) (* Giovanni Resta, Aug 01 2018 *)
CROSSREFS
Cf. A071128 (base 2) - A071135 (base 9), A069919 (base 10).
Sequence in context: A200830 A028545 A173943 * A031577 A031757 A195524
KEYWORD
base,nonn
AUTHOR
Erich Friedman, May 28 2002
EXTENSIONS
a(16)-a(20) from Giovanni Resta, Aug 01 2018
STATUS
approved