A130892 a(n) = n if n is not an odd prime number. Otherwise, a(n) = k*ceiling(n/10), where k is the smallest integer such that n < 10^k.

0, 1, 2, 1, 4, 1, 6, 1, 8, 9, 10, 4, 12, 4, 14, 15, 16, 4, 18, 4, 20, 21, 22, 6, 24, 25, 26, 27, 28, 6, 30, 8, 32, 33, 34, 35, 36, 8, 38, 39, 40, 10, 42, 10, 44, 45, 46, 10, 48, 49, 50, 51, 52, 12, 54, 55, 56, 57, 58, 12, 60, 14, 62, 63, 64, 65, 66, 14, 68

Offset: 1

Author

Mohammad K. Azarian, Aug 21 2007

Keywords

• nonn

Crossrefs

Cf. A131516, A130758, A000027, A001477, A006005.

Programs

Mathematica

Join[{0,1,2},Table[If[PrimeQ[n],IntegerLength[n]Ceiling[n/10],n],{n,3,99}]] (* Harvey P. Dale, Sep 14 2013 *)

Extensions

Offset corrected by Mohammad K. Azarian, Nov 19 2008