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A046439 9 steps needed to reach a prime under "Sum of digits raised to its digits' powers" procedure. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A028674 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

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Last modified May 11 19:29 EDT 2021. Contains 343808 sequences. (Running on oeis4.)