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.

A247315 Numbers x such that the sum of all their cyclic permutations is equal to that of all cyclic permutations of sigma(x).

Original entry on oeis.org

1, 15, 24, 69, 114, 133, 147, 153, 186, 198, 258, 270, 276, 288, 306, 339, 366, 393, 429, 474, 495, 507, 609, 627, 639, 717, 763, 817, 871, 1062, 1080, 1083, 1086, 1141, 1149, 1158, 1224, 1257, 1266, 1267, 1278, 1305, 1339, 1356, 1374, 1377, 1386, 1431, 1446
Offset: 1

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Author

Paolo P. Lava, Sep 12 2014

Keywords

Examples

			The sum of the cyclic permutations of 153 is 153 + 315 + 531 = 999; sigma(153) = 234 and the sum of its cyclic permutations is 234 + 423 + 342 = 999.
The sum of the cyclic permutations of 4731 is 4731 + 1473 + 3147 + 7314 = 16665; sigma(4731) = 6720 and the sum of its cyclic permutations is 6720 + 672 + 2067 + 7206 = 16665.
		

Crossrefs

Programs

  • Maple
    with(numtheory):P:=proc(q) local a,b,c,d,k,n;
    for n from 1 to q do a:=n; b:=a; c:=ilog10(a);
    for k from 1 to c do a:=(a mod 10)*10^c+trunc(a/10); b:=b+a; od;
    a:=sigma(n); d:=a; c:=ilog10(a);
    for k from 1 to c do a:=(a mod 10)*10^c+trunc(a/10); d:=d+a; od;
    if d=b then print(n); fi; od; end: P(10^9);
  • Mathematica
    scp[n_]:=Total[FromDigits/@Table[RotateRight[IntegerDigits[n],k],{k,IntegerLength[ n]}]]; Select[Range[1500],scp[#] == scp[DivisorSigma[ 1,#]]&] (* Harvey P. Dale, Nov 08 2020 *)