A267690 Numbers n such that replacing any single decimal digit d with d/3 produces a prime (obviously n can contain only digits 3, 6 or 9).

6, 9, 33, 63, 633

Offset

1,1

Links

Table of n, a(n) for n=1..5.

Example

633 belongs to this sequence because 631, 613 and 233 are all prime.

Mathematica

Select[FromDigits /@ Flatten[Map[Tuples[{3, 6, 9}, #] &, Range@ 3], 1], Function[n, AllTrue[Function[k, FromDigits@ MapAt[#/3 &, k, #] & /@ Range@ Length@ k]@ IntegerDigits@ n, And[PrimeQ@ #, # != n] &]]] (* Michael De Vlieger, Jan 20 2016, Version 10 *)

Crossrefs

Cf. A008585.

Sequence in context: A147415 A217048 A105866 * A084007 A046634 A166624

Adjacent sequences: A267687 A267688 A267689 * A267691 A267692 A267693

Keyword

nonn,base,fini,full

Author

Arkadiusz Wesolowski, Jan 19 2016

Status

approved