A342870 a(n) is the number of twin primes between A001359(n)^2 and A001359(n)*(A001359(n)+1).

1, 1, 0, 0, 1, 2, 2, 1, 2, 2, 0, 2, 4, 1, 1, 1, 5, 1, 3, 4, 2, 5, 4, 2, 4, 3, 6, 6, 3, 5, 6, 6, 4, 6, 4, 7, 9, 6, 8, 9, 6, 8, 10, 6, 11, 9, 13, 8, 12, 6, 14, 4, 7, 11, 11, 15, 9, 10, 12, 11, 10, 12, 13, 8, 15, 14, 11, 12, 9, 11, 15, 14, 18, 16, 11, 18, 10

Offset: 1

Author

Zhandos Mambetaliyev, Mar 28 2021

Keywords

• nonn

Crossrefs

Cf. A171727, A342552, A001359, A037074, A006094.

Programs

PARI

{for(k=1, 400, if(prime(k+1)-prime(k)==2, my(c=0); forprime(m=prime(k)^2, prime(k)*(prime(k)+1), c+=isprime(m+2)); print1(c, ", ")))}