A354972 Numbers k such that A354975(k) is prime.

2, 9, 15, 19, 21, 32, 63, 75, 77, 108, 115, 120, 147, 151, 229, 235, 243, 248, 252, 258, 279, 283, 285, 288, 290, 299, 303, 309, 314, 352, 360, 361, 362, 377, 382, 387, 393, 398, 413, 418, 430, 447, 457, 462, 465, 467, 468, 470, 475, 488, 510, 518, 551, 560, 569, 604, 625, 643, 679, 732, 735, 740

Offset

1,1

Comments

Numbers k such that Sum_{i=1..k} (prime(i+k) mod prime(i)) is prime.

Links

Robert Israel, Table of n, a(n) for n = 1..1000

Example

a(1) = 2 is a term because A354975(2) = (5 mod 2) + (7 mod 3) = 2 is prime.

Maple

filter:= proc(n) local k;
   isprime(add(ithprime(n+k) mod ithprime(k), k=1..n))
end proc:
select(filter, [$1..1000]);

Prog

(PARI) isok(k) = isprime(sum(i=1, k, prime(i+k) % prime(i))); \\ Michel Marcus, Jun 19 2022
(Python)
from itertools import count, islice
from sympy import prime, isprime
def A354972_gen(): # generator of terms
    for n in count(1):
        if isprime(sum(prime(i+n) % prime(i) for i in range(1, n+1))):
            yield n
A354972_list = list(islice(A354972_gen(), 10)) # Chai Wah Wu, Jun 20 2022

Crossrefs

Cf. A354975, A355009.

Sequence in context: A353317 A083288 A272044 * A304803 A184531 A063105

Adjacent sequences: A354969 A354970 A354971 * A354973 A354974 A354975

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Jun 15 2022

Status

approved