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A204341 Smith numbers with either no internal digits or all internal digits are 0. 1
4, 22, 27, 58, 85, 94, 202, 706, 8005, 80005, 700006, 800005, 7000000000000006, 80000000000000000005, 80000000000000000000005, 70000000000000000000000000006, 80000000000000000000000000000000000005, 700000000000000000000000000000000000000000000006 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 28 06:35 EST 2020. Contains 338699 sequences. (Running on oeis4.)