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A087714 Primes p = prime(i) such that p(i)# - p(i+1) and p(i)# + p(i+1) are both primes, where p# = A002110. 6
5, 13, 19, 367 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Conjecture: there are only 4 primes in this sequence.

LINKS

Table of n, a(n) for n=1..4.

EXAMPLE

2*3*5-7 = 23 is prime, 2*3*5+7 = 37 is prime.

PROG

(PARI) isok(p) = {if (isprime(p), my(pp = prod(k=1, primepi(p), prime(k)), q = nextprime(p+1)); isprime(pp-q) && isprime(pp+q); ); } \\ Michel Marcus, Sep 20 2019

(PARI) my(pr=1); forprime(p=1, , pr=pr*p; if(ispseudoprime(pr-nextprime(p+1)) && ispseudoprime(pr+nextprime(p+1)), print1(p, ", "))) \\ Felix Fröhlich, Sep 20 2019

CROSSREFS

Cf. A087715, A087716, A087728.

Cf. A002110.

Sequence in context: A175866 A227500 A265814 * A055045 A213741 A184825

Adjacent sequences:  A087711 A087712 A087713 * A087715 A087716 A087717

KEYWORD

nonn,more,changed

AUTHOR

Pierre CAMI, Sep 28 2003

STATUS

approved

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Last modified May 16 09:28 EDT 2021. Contains 343940 sequences. (Running on oeis4.)