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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
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
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jul 15 1998
STATUS
approved

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Last modified March 3 03:04 EST 2024. Contains 370499 sequences. (Running on oeis4.)