OFFSET
0,2
COMMENTS
The terms a(0), a(1), a(4) and a(9) confirm the primality of the terms included in A160432;
k assumes the value 1 when the value of n in a(n) is equal to 6*i or 6*i-1 where i is a positive integer.
EXAMPLE
a(0)= 1 so 6*1+1 = 7 is the minimum factor dividing 7; a(1)= 55 so 6*55+1 = 331 the minimum factor dividing 331; a(2)= 26 so 6*26+1 = 157 the minimum factor dividing 30301; a(3)= 5 so 6*5+1 = 31 the minimum factor dividing 3003001; a(10)=15333927 so 6*15333927+1 = 92003563 the minimum factor dividing 3*10^20+3*10^10+1.
CROSSREFS
KEYWORD
nonn
AUTHOR
Giacomo Fecondo, May 29 2010, May 30 2010
STATUS
approved