A128817 Primes which are 4 greater than the product of lesser twin primes.

7, 19, 81349, 3335149, 196773559, 13970922409, 150983758430839

Offset

1,1

Comments

Also primes which are 4 greater than A097489 terms where A097489 = product of first n terms of A001359 and A001359 = Lesser of twin primes.

Links

Table of n, a(n) for n=1..7.

Formula

Define twinl#(n)as the product of the first n lesser twin primes. Then if twinl#+4 is prime, list it.

Example

twinl#(2) = 3*5=15. 15+4 = 19 prime and the second term in the table.

Prog

(PARI) twiprimesl(n, a) = { local(pr, x, y, j); for(j=1, n, pr=1; for(x=1, j, pr*=twinl(x); ); y=pr+a; if(ispseudoprime(y), print1(y", ") ) ) } twinl(n) = \The n-th lower twin prime { local(c, x); c=0; x=1; while(c<n, if(isprime(prime(x)+2), c++); x++; ); return(prime(x-1)) }

Crossrefs

Sequence in context: A334982 A339698 A301808 * A284897 A209553 A037005

Adjacent sequences: A128814 A128815 A128816 * A128818 A128819 A128820

Keyword

nonn

Author

Cino Hilliard, May 08 2007

Status

approved