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A109302
Values of k such that prime(k)! + prime(k+1) is prime.
1
1, 2, 3, 4, 21, 93, 2029
OFFSET
1,2
COMMENTS
The primes of the form prime(n)!+prime(n+1) are in A094108.
If it exists, a(7) > 1397. - J.W.L. (Jan) Eerland, Nov 27 2022
EXAMPLE
4 is in the sequence because prime(4)=7, prime(5)=11 and 7!+11=5051 is prime.
MAPLE
a:=proc(n) if isprime(ithprime(n)!+ithprime(n+1))=true then n else fi end: seq(a(n), n=1..50);
MATHEMATICA
Select[Range[100], PrimeQ[Prime[#]!+Prime[#+1]]&] (* Harvey P. Dale, Jun 21 2021 *)
PROG
(PARI) isok(n) = isprime(prime(n)!+prime(n+1)); \\ Michel Marcus, Aug 20 2019
CROSSREFS
Cf. A094108.
Sequence in context: A058780 A183458 A109787 * A081480 A070841 A069801
KEYWORD
nonn,more
AUTHOR
Emeric Deutsch, Jun 24 2005
EXTENSIONS
a(7) from Michael S. Branicky, Aug 19 2024
STATUS
approved