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.

A247317 Numbers x such that the sum of all their cyclic permutations is equal to that of all cyclic permutations of sigma(x) and all cyclic permutations of Euler totient function phi(x).

Original entry on oeis.org

1, 2907, 3339, 3726, 4293, 4371, 4614, 5049, 5319, 5607, 5751, 6291, 17901, 18009, 18441, 19413, 20349, 20655, 20943, 21219, 21267, 21573, 21627, 22137, 22191, 23355, 24831, 25647, 25731, 26019, 26145, 26163, 27405, 27537, 28035, 28215, 28227, 28305, 29601, 30429
Offset: 1

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Author

Paolo P. Lava, Sep 12 2014

Keywords

Comments

Intersection of A247315 and A247316.
All numbers appear to be multiples of 3.
Big steps between a(135) and a(136), a(1387) and a(1388),...

Examples

			The sum of the cyclic permutations of 4371 is 4371 + 1437 + 7143 + 3714 = 16667; sigma(4371) = 6144 and the sum of its cyclic permutations is 6144 + 4614 + 4461 + 1446 = 16667; phi(4371) = 2760 and the sum of its cyclic permutations is2760+276+6027+7602 = 16667.
The sum of the cyclic permutations of 24831 is 24831 + 12483 + 31248 + 83124 + 48312 = 199998; sigma(24831) = 37440 and the sum of its cyclic permutations is 37440 + 3744 + 40374 + 44037 + 74403 = 199998; phi(24831) = 15840 and the sum of its cyclic permutations is 15840 + 1584 + 40158 + 84015 + 58401 = 199998.
		

Crossrefs

Programs

  • Maple
    with(numtheory):P:=proc(q) local a,b,c,d,f,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;
    a:=phi(n); f:=a; c:=ilog10(a);
    for k from 1 to c do a:=(a mod 10)*10^c+trunc(a/10); f:=f+a; od;
    if b=d and d=f then print(n); fi; od; end: P(10^9);