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A128824 First prime which is 2k greater than the product of lesser twin primes. 0
5, 7, 11, 13, 17, 19, 23, 37, 29, 31, 47, 37, 41, 43, 47, 61, 53, 67, 59, 61, 227, 67, 71, 73, 89, 79, 83, 97, 89, 103, 107, 97, 101, 103 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

In the example, 37 is the only number possible for 2k=22. Twinl#(1)= 3 and 3+22 = 25, not prime. Twinl#(n), n>2, is a multiple of 11 so adding 22 will always result in a multiple of 11 and not prime. If k is a multiple of a lesser twin prime, then the number of primes in twinl#(n)+2k is finite.

LINKS

Table of n, a(n) for n=1..34.

FORMULA

Define twinl#(n)as the product of the first n lesser twin primes. Then if twinl#+2k k=1,2,3... is prime, list it.

EXAMPLE

Twinl#(2) + 2*11 = 37, the first prime 22 greater than twinl#(2).

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: A118941 A096547 A216524 * A098420 A309726 A093495

Adjacent sequences:  A128821 A128822 A128823 * A128825 A128826 A128827

KEYWORD

nonn

AUTHOR

Cino Hilliard, May 08 2007

STATUS

approved

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Last modified July 27 13:36 EDT 2021. Contains 346306 sequences. (Running on oeis4.)