The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A071131 Squares which repeat with at least two full periods when written in base 5. 1

%I

%S 7056,71824,17380561,10479821641,1695422743056,3046710023334121,

%T 3484661204178361,4238552821180561,16390460540754756,

%U 2341118082098985289,49597060188790044841,413921144300672743056,931719854156507158681,1149780956458574459881,1254278391764733006841

%N Squares which repeat with at least two full periods when written in base 5.

%H Giovanni Resta, <a href="/A071131/b071131.txt">Table of n, a(n) for n = 1..23</a> (terms < 5^33)

%e 268^2 = 71824 = 424|424|4 in base 5.

%e 1302084^2 = 1695422743056 = 210234211|210234211 in base 5.

%t 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[5, #] & /@ Range[15]) (* _Giovanni Resta_, Aug 01 2018 *)

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

%K base,nonn

%O 1,1

%A _Erich Friedman_, May 28 2002

%E a(5)-a(15) from _Giovanni Resta_, Aug 01 2018

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 5 04:10 EST 2021. Contains 349530 sequences. (Running on oeis4.)