# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a354972 Showing 1-1 of 1 %I A354972 #28 Jun 20 2022 12:53:30 %S A354972 2,9,15,19,21,32,63,75,77,108,115,120,147,151,229,235,243,248,252,258, %T A354972 279,283,285,288,290,299,303,309,314,352,360,361,362,377,382,387,393, %U A354972 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 %N A354972 Numbers k such that A354975(k) is prime. %C A354972 Numbers k such that Sum_{i=1..k} (prime(i+k) mod prime(i)) is prime. %H A354972 Robert Israel, Table of n, a(n) for n = 1..1000 %e A354972 a(1) = 2 is a term because A354975(2) = (5 mod 2) + (7 mod 3) = 2 is prime. %p A354972 filter:= proc(n) local k; %p A354972 isprime(add(ithprime(n+k) mod ithprime(k), k=1..n)) %p A354972 end proc: %p A354972 select(filter, [$1..1000]); %o A354972 (PARI) isok(k) = isprime(sum(i=1, k, prime(i+k) % prime(i))); \\ _Michel Marcus_, Jun 19 2022 %o A354972 (Python) %o A354972 from itertools import count, islice %o A354972 from sympy import prime, isprime %o A354972 def A354972_gen(): # generator of terms %o A354972 for n in count(1): %o A354972 if isprime(sum(prime(i+n) % prime(i) for i in range(1,n+1))): %o A354972 yield n %o A354972 A354972_list = list(islice(A354972_gen(),10)) # _Chai Wah Wu_, Jun 20 2022 %Y A354972 Cf. A354975, A355009. %K A354972 nonn %O A354972 1,1 %A A354972 _J. M. Bergot_ and _Robert Israel_, Jun 15 2022 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE