A102245 Number of distinct prime factors of prime p concatenated p+1 times.

3, 3, 6, 5, 10, 8, 11, 11, 13, 20, 15, 6, 21, 15, 22, 18, 26

Offset

1,1

Links

Table of n, a(n) for n=1..17.

Dario Alejandro Alpern, Factorization using the Elliptic Curve Method.

Example

At p=2, the number of distinct prime factors of 222 is 3.
At p=3, the number of distinct prime factors of 3333 is 3.
At p=5, the number of distinct prime factors of 555555 is 6.
At p=7, the number of distinct prime factors of 77777777 is 5.

Mathematica

f[n_] := Length[ FactorInteger[ FromDigits[ Flatten[ Table[ IntegerDigits[ Prime[n]], {Prime[n] - 1}]] ]]]; Table[ f[n], {n, 17}] (* Robert G. Wilson v, Feb 21 2005 *)

Crossrefs

Cf. A101081, A102246.

Sequence in context: A257143 A080512 A225441 * A038167 A307967 A131077

Adjacent sequences: A102242 A102243 A102244 * A102246 A102247 A102248

Keyword

nonn,base

Author

Parthasarathy Nambi, Feb 18 2005

Extensions

More terms from Robert G. Wilson v, Feb 21 2005

Status

approved