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Numbers n such that the "inventory" A063850 of n is a palindrome.
1

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

%S 1,22,112,121,211,333,1113,1131,1311,3111,4444,11114,11141,11411,

%T 14111,22233,22323,22332,23223,23232,23322,32223,32232,32322,33222,

%U 41111,55555

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

%H <a href="http://www.primepuzzles.net/puzzles/puzz_207.htm">The Inventory Sequences and Self-Inventoried Numbers</a> in www.primepuzzles.net

%e The "inventory" of 112 is 2112 (two "1"s, one "2"), which is a palindrome. Hence 112 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]]; isPalin[n_] := (n == FromDigits[Reverse[IntegerDigits[n]]]); Select[Range[10^5], isPalin[g[ # ]] &]

%Y Cf. A063850. Different from A079676.

%K base,nonn

%O 1,2

%A _Joseph L. Pe_, Jan 14 2003