OFFSET
1,1
COMMENTS
This sequence is infinite if Dickson's conjecture holds. - Charles R Greathouse IV, Apr 23, 2011
This is actually the complete list of primes starting a CPAP-4 (set of 4 consecutive primes in arithmetic progression). It equals A033451 for a(1..24), but it contains a(25) = 74453 which starts a CPAP-4 with common difference 18 (the first one with a difference > 6) and therefore is not in A033451. - M. F. Hasler, Oct 26 2018
LINKS
Zak Seidov and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 4000 terms from Seidov)
EXAMPLE
a(1) = 251 = prime(54) = A000040(54) and prime(55) - prime(54) = prime(56)-prime(55) = 6. - Zak Seidov, Apr 23 2011
MATHEMATICA
Select[Partition[Prime[Range[9000]], 4, 1], Length[Union[Differences[#]]] == 1&][[All, 1]] (* Harvey P. Dale, Aug 08 2017 *)
PROG
(PARI) p=2; q=3; r=5; forprime(s=7, 1e4, t=s-r; if(t==r-q&&t==q-p, print1(p", ")); p=q; q=r; r=s) \\ Charles R Greathouse IV, Feb 14 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Henry Bottomley, Apr 10 2000
STATUS
approved