

A120335


CRF(13): consecutive refactorable numbers (rf, rf1 are refactorable) such that 13 is the smallest prime divisor of rf.


0




OFFSET

1,1


COMMENTS

The sequence has prime factorization (13*197)^12, (13*1093)^12, (13*1733)^12, (13*17*139)^12, (13*7877)^12, (13*16069)^12.


LINKS

Table of n, a(n) for n=1..3.


FORMULA

a(n) = is the nth number rf such that both rf and rf1 are refactorable and 13 is the smallest prime divisor of rf.


EXAMPLE

a(1)=(13*197)^12 is the first number rf such that rf refactorable, 13 is the smallest prime of rf and rf1 is refactorable.


CROSSREFS

Cf. A033950, A036898, A114617.
Sequence in context: A095474 A003944 A003937 * A095476 A292856 A292846
Adjacent sequences: A120332 A120333 A120334 * A120336 A120337 A120338


KEYWORD

nonn,bref


AUTHOR

Walter Kehowski, Jun 22 2006


STATUS

approved



