A131516 -id:A131516 - cp's OEIS frontend

A130758 a(n) = n if n is not an odd prime number. Otherwise, a(n) = k, where k is the smallest integer such that n < 10^k.

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

Offset: 1

Mohammad K. Azarian, Aug 17 2007

nonn

Cf. A000027, A001477, A006005, A131516.

Table[If[OddQ[n]&&PrimeQ[n],IntegerLength[n],n],{n,0,70}] (* Harvey P. Dale, Apr 13 2016 *)

Offset corrected by Mohammad K. Azarian, Nov 19 2008

A130891 a(n) = n if n is not an odd prime number. Otherwise, a(n) = k*floor(n/10), where k is the smallest integer such that n < 10^k.

Original entry on oeis.org

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

Offset: 0

Mohammad K. Azarian, Aug 21 2007

nonn

Harvey P. Dale, Table of n, a(n) for n = 0..1000

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

f:= proc(n) local k;
  if n::odd and isprime(n) then
    k:= ilog10(n)+1;
    k*floor(n/10)
  else n
  fi
end proc:
map(f, [$0..100]); # Robert Israel, Aug 04 2019

Table[If[n>2&&PrimeQ[n],IntegerLength[n]Floor[n/10],n],{n,0,70}] (* Harvey P. Dale, Mar 31 2025 *)

Offset changed by Mohammad K. Azarian, Nov 19 2008

Offset corrected by Robert Israel, Aug 04 2019

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.

Original entry on oeis.org

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

Mohammad K. Azarian, Aug 21 2007

nonn

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

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

Offset corrected by Mohammad K. Azarian, Nov 19 2008

cp's OEIS Frontend

A130758 a(n) = n if n is not an odd prime number. Otherwise, a(n) = k, where k is the smallest integer such that n < 10^k.

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A130891 a(n) = n if n is not an odd prime number. Otherwise, a(n) = k*floor(n/10), where k is the smallest integer such that n < 10^k.

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Maple

Mathematica

Extensions

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.

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Author

Keywords

Crossrefs

Programs

Mathematica

Extensions