OFFSET

1,2

LINKS

Dario A. Alpern, Factorization using the Elliptic curve method.

FORMULA

EXAMPLE

For n=2, the number of distinct prime factors of 4444 is 3.

For n=3, the number of distinct prime factors of 666666 is 6.

For n=4, the number of distinct prime factors of 88888888 is 5.

For n=5, the number of distinct prime factors of 999999999 is 3.

MAPLE

read("transforms") ;

A102621 := proc(n) c := A018252(n) ; x := c ; for j from 2 to c do x := digcat2(x, c) ; end do; A001221(x) ; end proc: # R. J. Mathar, Aug 24 2011

MATHEMATICA

PrimeNu/@(FromDigits/@(Flatten[Table[IntegerDigits[#], #]]&/@Select[ Range[ 40], !PrimeQ[#]&])) (* Harvey P. Dale, Sep 03 2018 *)

CROSSREFS

KEYWORD

nonn,base,less

AUTHOR

Parthasarathy Nambi, Jan 31 2005

EXTENSIONS

More terms from Harvey P. Dale, Sep 03 2018

STATUS

approved