login
A156148
Numbers k such that prime(prime(k)) + 2 == 0 (mod prime(k)), where prime(p)=A000040(p) is the p-th prime.
1
5, 20, 51891, 51893
OFFSET
1,1
COMMENTS
No additional terms up to k=500,000. - Harvey P. Dale, Jul 12 2022
FORMULA
a(n) = A000720(A156149(n)).
MATHEMATICA
Select[Range[52000], Mod[Prime[Prime[#]]+2, Prime[#]]==0&] (* Harvey P. Dale, Jul 12 2022 *)
PROG
(PARI) p=c=0; until(0, until( isprime(c++), p=nextprime(p+1)); (p+2)%c & next; print1( primepi(c)", "))
CROSSREFS
Cf. A156155.
Sequence in context: A213148 A202860 A344709 * A224867 A156824 A053002
KEYWORD
hard,more,nonn
AUTHOR
M. F. Hasler, Feb 04 2009
STATUS
approved