A204341 Smith numbers with either no internal digits or all internal digits are 0.

4, 22, 27, 58, 85, 94, 202, 706, 8005, 80005, 700006, 800005, 7000000000000006, 80000000000000000005, 80000000000000000000005, 70000000000000000000000000006, 80000000000000000000000000000000000005, 700000000000000000000000000000000000000000000006

Offset

1,1

Comments

All semiprimes of the form 7*10^n + 6 and 8*10^n + 5 are in the sequence.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..34

Eric Weisstein's World of Mathematics, Smith Number

Mathematica

e = 47; Sort[Join[{27}, 2*Select[Flatten[Union[Table[(2*10^n + 2)/2, {n, 0, e}], Table[(a*10^n + 13 - a)/2, {a, {5, 7, 9}}, {n, e}]]], PrimeQ], 5*Select[Table[(8*10^n + 5)/5, {n, e}], PrimeQ]]]

Crossrefs

Cf. A006753.

Sequence in context: A279314 A006753 A098836 * A036920 A036921 A083510

Adjacent sequences: A204338 A204339 A204340 * A204342 A204343 A204344

Keyword

base,nonn

Author

Arkadiusz Wesolowski, Jan 14 2012

Status

approved