A339675 a(n) is the least m such that A340226(m) = 2*n.

3, 4, 6, 275, 13, 19, 180, 182, 10, 274, 127, 24, 1214, 136, 22, 2918, 308, 50, 490, 44, 9, 243, 65, 62, 902, 31, 54, 232, 296, 28, 890, 319, 30, 717, 25, 157, 1045, 254, 48, 698, 190, 181, 2821, 498, 58, 2033, 2312, 236, 450, 82, 154, 699, 286, 611, 1530, 434, 581, 2780, 801, 17, 4373, 158, 71

Offset

1,1

Comments

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

Links

Robert Israel, Table of n, a(n) for n = 1..600

Example

For n=4, A340226(275) = 8, and this is the first appearance of 8 in A340226, so a(4) = 275.

Maple

V:= Vector(100): count:= 0:
q:= 3: r:= 5:
for i from 3 while count < 100 do
  p:= q; q:= r; r:= nextprime(r);
  for k from 2 by 2 do
    if isprime(k*q-p) and isprime(k*q-r) then break fi;
  od;
  v:= k/2;
  if v <= 100 and V[v] = 0 then count:= count+1; V[v]:= i; fi
od:
convert(V, list);

Crossrefs

Cf. A340226.

Sequence in context: A332511 A129293 A233512 * A095877 A024476 A372366

Adjacent sequences: A339672 A339673 A339674 * A339676 A339677 A339678

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Jan 01 2021

Status

approved