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A350190
Numbers k such that A083723(k) is prime.
1
1, 2, 3, 4, 5, 6, 15, 16, 17, 19, 20, 21, 22, 23, 28, 31, 34, 36, 39, 40, 42, 46, 49, 51, 52, 56, 63, 70, 72, 73, 75, 77, 81, 82, 86, 89, 90, 92, 96, 108, 112, 113, 115, 116, 117, 118, 129, 130, 132, 139, 145, 154, 156, 157, 164, 168, 169, 172, 181, 183, 184, 198, 201, 205, 206, 207, 213, 215
OFFSET
1,2
COMMENTS
Numbers k such that k*prime(k)+k-1 is prime.
LINKS
EXAMPLE
a(7) = 15 is a term because A083723(15) = 15*47+14 = 719 is prime.
MAPLE
select(n -> isprime(n*ithprime(n)+n-1), [$1..1000]);
MATHEMATICA
Select[Range[200], PrimeQ[(Prime[#] + 1)*# - 1] &] (* Amiram Eldar, Dec 19 2021 *)
PROG
(PARI) isok(k) = isprime(k*prime(k)+k-1); \\ Michel Marcus, Dec 19 2021
CROSSREFS
Cf. A083723.
Sequence in context: A085157 A065637 A325805 * A039061 A138987 A318534
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Dec 19 2021
STATUS
approved