A046439 9 steps needed to reach a prime under "Sum of digits raised to its digits' powers" procedure.

133, 138, 183, 303, 308, 313, 318, 330, 331, 380, 381, 389, 398, 446, 464, 644, 789, 798, 803, 813, 830, 831, 839, 879, 893, 897, 938, 978, 983, 987, 1005, 1015, 1024, 1042, 1046, 1050, 1051, 1064, 1105, 1115, 1124, 1142, 1146, 1150, 1151, 1164, 1204

Offset

0,1

Links

Table of n, a(n) for n=0..46.

Mathematica

sop[n_] := Total[#^# & /@ (IntegerDigits[n] /. {0 -> 1})]; Select[Range[1205], (z = Boole /@ PrimeQ[Rest[NestList[sop, #, 9]]])[[9]] - Total[Drop[z, -1]] == 1 &] (* Jayanta Basu, Jun 25 2013 *)

Crossrefs

Cf. A046431.

Sequence in context: A369820 A246561 A003915 * A031188 A102619 A020446

Adjacent sequences: A046436 A046437 A046438 * A046440 A046441 A046442

Keyword

nonn,base

Author

Patrick De Geest, Jul 15 1998

Status

approved