A341631 Numbers k such that A073837(k) is prime.

2, 7, 9, 14, 19, 27, 28, 29, 30, 36, 44, 60, 61, 68, 70, 71, 87, 88, 89, 100, 101, 104, 105, 108, 109, 112, 113, 138, 157, 174, 192, 193, 199, 201, 202, 203, 204, 210, 274, 275, 276, 277, 304, 305, 306, 364, 365, 366, 372, 373, 384, 387, 388, 389, 399, 400, 401, 405, 471, 472, 473, 511, 512, 513

Offset

1,1

Comments

Numbers k such that the sum of primes from k to 2*k is prime.

Links

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

Example

a(3) = 9 is in the sequence because A073837(9) = 11+13+17 = 41 is prime.

Maple

R:= 2: S:= [2, 3]: s:= 5: q:= 5: count:= 1:
for n from 3 while count < 100 do
  if n = S[1]+1 then S:= S[2..-1]; s:= s-n+1 fi;
  if q <= 2*n then S:= [op(S), q]; s:= s+q; q:= nextprime(q) fi;
  if isprime(s) then count:= count+1; R:= R, n;  fi;
od:
R;

Crossrefs

Cf. A073837, A341280, A341632.

Sequence in context: A184400 A074244 A190565 * A102994 A226824 A168132

Adjacent sequences: A341628 A341629 A341630 * A341632 A341633 A341634

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Feb 16 2021

Status

approved