A054690 n consecutive primes differ by 4 or more starting at a(n), or n consecutive primes with no twin primes.

7, 19, 43, 73, 73, 349, 349, 349, 349, 349, 349, 661, 661, 661, 661, 661, 661, 661, 661, 8629, 8629, 8629, 8629, 13399, 13399, 13399, 14629, 14629, 24421, 24421, 24421, 24421, 24421, 24421, 24421, 24421, 24421, 24421, 24421, 24421, 24421

Offset

2,1

Links

Robert Israel, Table of n, a(n) for n = 2..204

Maple

P:= select(isprime, [seq(i, i=3..10^7, 2)]):
A:= 'A':
state:= 0: smax := 0:
for i from 2 to nops(P) do
  if P[i] - P[i-1] >= 4 then
    state:= state + 1;
    if state > smax then smax:= state; A[state+1]:= P[i-state] fi
  else
    state:= 0;
  fi
od:
seq(A[i], i=2..smax+1); # Robert Israel, Jun 27 2017

Mathematica

Prime[#]&/@With[{pd=If[#>2, 1, 0]&/@Differences[Prime[Range[3000]]]}, Flatten[ Table[ SequencePosition[pd, PadRight[{}, n, 1], 1][[All, 1]], {n, 45}]]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 29 2018 *)

Crossrefs

Cf. A054691, A054692.

Sequence in context: A104163 A145993 A265676 * A259486 A298034 A054691

Adjacent sequences: A054687 A054688 A054689 * A054691 A054692 A054693

Keyword

nonn

Author

Jeff Burch, Apr 19 2000

Status

approved