cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A061839 a(n+1) is the smallest square ending with a(n), initial term is 5.

Original entry on oeis.org

5, 25, 225, 1225, 81225, 16281225, 7077116281225, 1642681227077116281225, 228822983661635570881642681227077116281225, 976324672198183536165095004791768497036228822983661635570881642681227077116281225
Offset: 1

Views

Author

Amarnath Murthy, May 29 2001

Keywords

Links

Crossrefs

Cf. A050634, A065689, A065780, A065781, A050636, A050638.

Extensions

Corrected and extended by Frank Ellermann, Jun 04 2001
More terms from Ulrich Schimke (ulrschimke(AT)aol.com), Dec 18 2001
Edited by N. J. A. Sloane, Apr 29 2007
First term prepended by Derek Orr, Dec 27 2013

A065781 a(1) = 25; for n > 1, a(n) is the smallest integer > 0 such that the concatenation a(n)a(n-1)...a(2)a(1) is a square.

Original entry on oeis.org

25, 2, 1, 8, 162, 70771, 164268122, 22882298366163557088, 976324672198183536165095004791768497036, 67395729561035485747722358417684895847812434249174374011671902126543092988774
Offset: 1

Views

Author

Klaus Brockhaus, Nov 19 2001

Keywords

Crossrefs

Cf. A061359, A065691, A061839, A065780.

Extensions

More terms from Ulrich Schimke (ulrschimke(AT)aol.com), Dec 18 2001

A065808 Square of n has a smaller square as its final digits.

Original entry on oeis.org

7, 8, 9, 10, 11, 12, 13, 15, 17, 18, 19, 20, 21, 22, 23, 25, 27, 28, 29, 30, 31, 32, 33, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 67, 68, 69, 70, 71, 72, 73, 75, 77, 78, 79, 80, 81, 82, 83, 85, 87, 88
Offset: 1

Views

Author

Klaus Brockhaus, Nov 22 2001

Keywords

Comments

Includes all n >= 7 not == 4 or 6 (mod 10). - Robert Israel, Oct 24 2017

Links

Crossrefs

A065807 gives the corresponding squares.
Cf. A065690, A050635, A050637, A050639, A065777, A065780, A065783, A065786, A065789, A065792.

Programs

  • Maple
    filter:= n ->
  ormap(t -> issqr(n^2 mod 10^t), [$1..ilog10(n^2)]):
select(filter, [$1..100]); # Robert Israel, Oct 24 2017
  • Mathematica
    ds[n_] := NestWhileList[FromDigits[Rest[IntegerDigits[#]]] &, n, # > 9 &]; Select[Range[4, 88], Or @@ IntegerQ /@ Sqrt[Rest[ds[#^2]]] &] (* Jayanta Basu, Jul 10 2013 *)
  • PARI
    a065808(m) = local(k, a, b, d, j, n, r); for(k=1, m, a=length(Str(n))-1; b=1; j=1; n=k^2; while(b, d=divrem(n, 10^j); if(d[1]>0&&issquare(d[2]), b=0; issquare(n, &r); print1(r, ","), if(j

Extensions

Offset changed to 1 by Robert Israel, Oct 24 2017
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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