A368960 a(n) is the least prime of the form k*n + (greatest square < k*n).

3, 3, 13, 5, 19, 61, 11, 113, 13, 19, 467, 61, 101, 23, 109, 113, 59, 61, 359, 109, 37, 467, 173, 601, 41, 101, 103, 53, 107, 109, 599, 113, 757, 59, 1009, 61, 73, 359, 601, 761, 163, 739, 79, 757, 349, 173, 83, 1297, 179, 181, 2797, 101, 521, 103, 1181, 1297, 541, 107, 461, 109, 727, 599, 739

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(3) = 13 because 13 = 3 * 3 + 4 is prime, where 4 is the greatest prime < 3 * 3, while 1 * 3 + 1 = 4 and 2 * 3 + 4 = 10 are not prime.

Maple

g:= n -> n + floor(sqrt(n-1))^2:
f:= proc(n) local k, v;
  for k from n by n do
     v:= g(k);
     if isprime(v) then return v fi;
   od;
end proc:
map(f, [$1..100]);

Crossrefs

Sequence in context: A076509 A206704 A020550 * A306529 A200921 A135949

Adjacent sequences: A368957 A368958 A368959 * A368961 A368962 A368963

Keyword

nonn,look

Author

Robert Israel, Jan 10 2024

Status

approved