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A120639 Primes such that their quadruple is 1 away from a prime number. 3
2, 3, 5, 7, 11, 13, 17, 37, 41, 43, 53, 67, 71, 73, 79, 83, 97, 127, 131, 137, 139, 163, 173, 193, 197, 199, 227, 263, 277, 281, 293, 307, 373, 383, 409, 431, 433, 467, 487, 499, 503, 521, 563, 577, 587, 593, 617, 619, 673, 677, 683, 701, 709, 727, 739, 743, 797 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence is a variation of the sequence in the reference. However, this sequence should have an infinite number of terms. k=2 in the PARI code.

REFERENCES

R. Crandall and C. Pomerance, Prime Numbers A Computational Perspective, Springer Verlag 2002, p. 49, exercise 1.18.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

17*4 = 68, one away from 67 which is prime.

MATHEMATICA

Select[Prime[Range[200]], Or@@PrimeQ[4#+{1, -1}]&] (* Harvey P. Dale, Feb 18 2013 *)

PROG

(PARI) primepm2(n, k) = \k = number of iterations, k = factor { local(x, p1, p2, f1, f2, r); if(k%2, r=2, r=1); for(x=1, n, p1=prime(x); p2=prime(x+1); if(isprime(p1*k+r)||isprime(p1*k-r), print1(p1", ") ) ) }

CROSSREFS

Sequence in context: A321420 A118725 A117835 * A141263 A016114 A263499

Adjacent sequences:  A120636 A120637 A120638 * A120640 A120641 A120642

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Aug 17 2006

STATUS

approved

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Last modified September 18 16:55 EDT 2020. Contains 337170 sequences. (Running on oeis4.)