A224325 First of three consecutive primes in arithmetic progression with gap of 6n, and such that a(n) > a(n-1).

47, 199, 20183, 40039, 69593, 255767, 689467, 3565931, 6314393, 9113263, 12012677, 23346737, 43607351, 69266033, 75138781, 324237847, 460475467, 652576321, 742585183, 747570079, 807620651, 2988119207, 12447231761

Offset

1,1

Comments

Without the condition on monotonicity, this would be essentially the same as A052187, but there 255767 is followed by 247099, while monotonicity here gives 689467. Similarly, following a(9) = A052187(10) = 6314393 we have a(10) = 9113263, while A052187(11) = 4911251. The next term which is not matching is a(14) = 69266033 vs A052187(15) = 34346203. One may notice that the two terms differ approximately by a factor of 2.

Links

Pierre CAMI, Table of n, a(n) for n = 1..23

Example

a(1) = A047948(1) = 47 is the least prime p(k) such that p(k+1) - p(k) = p(k+2) - p(k+1) = 6.
a(2) = A052188(1) = 199 is the least prime p(k) > 47 such that p(k+1) - p(k) = p(k+2) - p(k+1) = 12.
a(3) = A052189(1) = 20183 is the least prime p(k) > 199 such that p(k+1) - p(k) = p(k+2) - p(k+1) = 18.
a(4) = A052190(1) = 40039 is the least prime p(k) > 20183 such that p(k+1) - p(k) = p(k+2) - p(k+1) = 24.
a(5) = A052195(1) = 69593 is the least prime p(k) > 40039 such that p(k+1) - p(k) = p(k+2) - p(k+1) = 30.

Prog

(PARI) g=6; o=2; forprime(p=2, , o+g==(o=p)||next; nextprime(p+1)==p+g||next; print1(p-g", "); g+=6)

Crossrefs

Cf. A224324 (gaps of 30n).

Sequence in context: A065532 A157362 A141874 * A211335 A142203 A067986

Adjacent sequences: A224322 A224323 A224324 * A224326 A224327 A224328

Keyword

nonn

Author

M. F. Hasler, Apr 03 2013

Status

approved