OFFSET
1,4
COMMENTS
p(n) is the n-th prime; # denotes primorial (A002110).
a(n) seems to grow like 2*log(p(n)).
LINKS
Jinyuan Wang, Table of n, a(n) for n = 1..100
EXAMPLE
a(5) = 3 because for (j,k) = (1,3),(10,4),(8,5), j*(11#/3)/p(k)+-3 are consecutive primes.
PROG
(PARI) a(n) = {my(p=vector(n, i, prime(i)), x, y=2*prod(i=3, n, p[i])); sum(j=1, prime(n+1)-1, sum(k=3, n, j%p[k]>0 && ispseudoprime(x=j*y/p[k]-3) && nextprime(x+1)==x+6)); } \\ Jinyuan Wang, Mar 20 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Oct 29 2003
EXTENSIONS
Edited by Don Reble, Nov 16 2005
STATUS
approved