A120335 - OEIS

%I #6 Mar 30 2012 18:36:04

%S 79600343456925208350554324952070658488321,

%T 67727051825754224132985695308485992267126791150081,

%U 17096333467784942360991864487916588941402614691799041

%N CRF(13): consecutive refactorable numbers (rf, rf-1 are refactorable) such that 13 is the smallest prime divisor of rf.

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

%F a(n) = is the n-th number rf such that both rf and rf-1 are refactorable and 13 is the smallest prime divisor of rf.

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

%Y Cf. A033950, A036898, A114617.

%K nonn,bref

%O 1,1

%A _Walter Kehowski_, Jun 22 2006