A340211 a(n) is the least m such that A340210(m) = 2*n.

2, 55, 3, 10, 179, 7, 35, 274, 4, 241, 15, 23, 128, 452, 12, 425, 339, 9, 38, 239, 32, 262, 708, 6, 98, 118, 33, 279, 437, 24, 122, 419, 13, 604, 110, 131, 924, 1161, 41, 83, 2210, 62, 310, 987, 63, 418, 621, 18, 1569, 202, 225, 833, 1947, 125, 1477, 2486, 25, 1057, 3469, 34, 1226, 1544, 64, 1236

Offset

1,1

Comments

2*n*prime(a(n))+prime(a(n)+1) and 2*n*prime(a(n))+prime(a(n)+2) are prime.

Links

Robert Israel, Table of n, a(n) for n = 1..603

Example

For n=4, A340210(10)=8 and this is the first appearance of 8 in A340210, so a(4)=10.

Maple

f:= proc(n) local p, q, r, k;
  p:= ithprime(n);
  q:= ithprime(n+1);
  r:= ithprime(n+2);
  for k from 2 by 2 do
    if isprime(k*p+q) and isprime(k*p+r) then return k fi
  od
end proc:
V:= Vector(100): count:= 0:
for n from 2 while count < 100 do v:= A[n]/2;
  if v <= 100 and V[v] = 0 then V[v]:= n; count:= count+1 fi
od:

Crossrefs

Cf. A340210, A340214.

Sequence in context: A359183 A089180 A034013 * A356985 A280209 A157262

Adjacent sequences: A340208 A340209 A340210 * A340212 A340213 A340214

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Dec 31 2020

Status

approved