cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A342552 The number of twin primes between prime(i)*prime(i+1) and prime(i+1)*prime(i+2) where prime(i) and prime(i+1) are twin primes.

Original entry on oeis.org

2, 3, 4, 3, 5, 6, 9, 11, 8, 12, 24, 19, 34, 14, 27, 14, 28, 17, 46, 26, 24, 55, 28, 14, 86, 50, 38, 66, 28, 67, 76, 41, 64, 40, 43, 93, 53, 87, 67, 48, 89, 66, 42, 72, 69, 76, 49, 76, 42, 49, 59, 73, 260, 109, 145, 169, 70, 137, 193, 292
Offset: 1

Views

Author

Zhandos Mambetaliyev, Mar 27 2021

Keywords

Crossrefs

Cf. A171727, A006094, A001359, A006512, A037074.

Programs

  • PARI
    {for(n=1,200, if(prime(n+1)-prime(n)==2, my(a=prime(n)*prime(n+1), b=prime(n+1)*prime(n+2), c=0); for(m=a,b, if(isprime(m)==1&&isprime(m+2)==1, c=c+1)); print1(c, ", ")))}

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

Original entry on oeis.org

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

Views

Author

Zhandos Mambetaliyev, Mar 28 2021

Keywords

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, ", ")))}
Showing 1-2 of 2 results.

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