A079464 - OEIS

%I #3 Feb 11 2014 19:05:41

%S 1,3,7,9,17,23,27,33,39,51,63,69,81,93,99,111,113,127,131,133,137,193,

%T 199,203,209,223,232,233,271,299,301,311,313,331,359,361,367,371,377,

%U 414,431,433,439,441,447,451,463,469,474,477,479,481,497,499,503,523

%N Numbers n such that the "inventory" A063850 of n is prime.

%H Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_207.htm">The Inventory Sequences and Self-Inventoried Numbers</a>, (see Question 7)

%e The "inventory" of 299 is 1229 (one "2", two "9"s), which is prime. Hence 299 belongs to the sequence.

%t g[n_] := Module[{seen, r, d, l, i, t}, seen = {}; r = {}; d = IntegerDigits[n]; l = Length[d]; For[i = 1, i <= l, i++, t = d[[i]]; If[ ! MemberQ[seen, t], r = Join[r, IntegerDigits[Count[d, t]]]; r = Join[r, {t}]; seen = Append[seen, t]]]; FromDigits[r]]; Select[Range[10^3], PrimeQ[g[ # ]] &]

%Y Cf. A063850.

%K base,nonn

%O 1,2

%A _Joseph L. Pe_, Jan 14 2003