A309232 First occurrence of n in A308479 or 0 if impossible.

99, 1, 12, 25, 47, 96, 137, 125, 81, 306, 0, 89, 389, 289, 357, 589, 432, 1152, 216, 2054, 297, 91, 1319, 2108, 1204, 1594, 1523, 1093, 1064, 1689, 1297, 1275, 1521, 2086, 1738, 1698, 1374, 1054, 1315, 1253, 497, 1949, 1163, 697, 4517, 871, 1513, 1475, 1228, 1613, 397, 963, 945

Offset

0,1

Comments

Impossible numbers below 10000 are 1000, 10000, and numbers == 10 mod(100), == 89 mod(100), == 100 (mod 1000), or == 899 (1000).

Links

Table of n, a(n) for n=0..52.

Mathematica

f = Compile[{{n, _Integer}}, Module[{k = 1, id1 = DeleteCases[IntegerDigits[n], 0], id2 = DeleteCases[IntegerDigits[2 n], 0]}, While[k < 10001 && Intersection[id1, id2] != {}, id1 = id2; k++; id2 = DeleteCases[Union[IntegerDigits[(k + 1) n]], 0]]; If[k == 10001, 0, k]]]; t[_] := -1; k = 1; While[k < 33001, a = f@k; If[t[a] == -1, t[a] = k; Print[{a, k}]]; k++]; (t@# & /@ Range[0, 100]) /. {-1 -> 0}

Crossrefs

Cf. A308479.

Sequence in context: A113602 A097846 A246222 * A360376 A304140 A305046

Adjacent sequences: A309229 A309230 A309231 * A309233 A309234 A309235

Keyword

nonn,base

Author

David Radcliffe, Daniel Griller, and Robert G. Wilson v, Jul 16 2019

Status

approved