A340354 a(n) is the sum, for j < n coprime to n, of the least prime > n congruent to j (mod n).

3, 12, 12, 50, 18, 112, 64, 126, 60, 330, 72, 520, 182, 240, 240, 884, 198, 1368, 320, 588, 462, 1886, 360, 1650, 676, 1296, 644, 3074, 390, 4030, 1248, 1848, 1292, 2380, 864, 5328, 1596, 2496, 1280, 6560, 840, 7740, 2112, 2880, 2530, 9588, 1632, 7938, 2250, 4896, 3224, 12402, 1890, 6820, 2968

Offset: 2

Author

J. M. Bergot and Robert Israel, Jan 05 2021

Keywords

• nonn
• look

Comments

For each n >= 3, a(n) is divisible by n.

Examples

			For n=6 the primes are 7 == 1 (mod 6) and 11 == 5 (mod 6), so a(6) = 7+11=18.
		

Links

• Robert Israel, Table of n, a(n) for n = 2..3000

Crossrefs

Row sums of A060940 (starting with second row).

Programs

Maple

f:= proc(n) local t, k,p;
  t:= 0:
  for k from 1 to n-1 do
   if igcd(k,n) = 1 then
     for p from n+k by n do
       if isprime(p) then
         t:= t+p;
         break
       fi
     od
   fi
  od;
  t
end proc:
map(f, [$2..100]);