OFFSET
1,1
LINKS
FORMULA
a(n) = min {k}: A034693(a(n)) is an even number such that in a(n)*k+1 progression the first prime occurs at even 2n=k position.
EXAMPLE
First example: a(1)=3 since in 3k+1 sequence, the first term is 3, a prime and the d=2 is the smallest such difference. The next such progression is 5k+1 because 5*2+1=11 is prime. 2nd example: here at n=6 a(6)=59. This means that 2n=12 occurs first in A034693 at its position 59, which means that its first prime is 12*59+1=709. arises as 12th term (such progressions are: 59k+1,85k+1,133k+1, etc.)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved