Number of values of k for which sigma(k) is a permutation of decimal digits of k, for k < 2^n.
A216392
Number of values of k for which sigma(k) is a permutation of decimal digits of k, for k < 2^n.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =2a(7) =2a(8) =5a(9) =7a(10) =7a(11) =13a(12) =16a(13) =21a(14) =35a(15) =57a(16) =83a(17) =143a(18) =207a(19) =278a(20) =457a(21) =790a(22) =1064a(23) =1815a(24) =3468a(25) =5194a(26) =8226
External references
- oeis: A216392