A097439 Least k such that k*prime(n)#/3 - 3 and k*prime(n)#/3 + 3 are consecutive primes, where prime(n)# is the n-th primorial.

39, 13, 5, 8, 7, 23, 8, 2, 35, 41, 4, 56, 37, 37, 89, 70, 443, 109, 79, 149, 116, 224, 10, 167, 31, 32, 250, 335, 383, 121, 61, 134, 41, 224, 545, 1229, 29, 253, 127, 47, 79, 32, 991, 466, 31, 1124, 634, 374, 1358, 730, 587, 119, 1375, 1303, 1102, 119, 647, 650, 265

Offset

1,1

Links

Table of n, a(n) for n=1..59.

Example

39*2/3 = 26, 23 and 29 are consecutive primes so a(1) = 39.
13*2*3/3 = 26 so a(2) = 13.

Mathematica

a[n_] := Module[{k = 1, p = Product[Prime[i], {i, 1, n}]}, While[!(PrimeQ[k*p/3-3] && NextPrime[k*p/3-3] == k*p/3+3), k++]; k]; Array[a, 60] (* Amiram Eldar, Jul 17 2021 *)

Crossrefs

Cf. A002110.

Cf. A097440, A097441, A097570, A098064.

Sequence in context: A103479 A036174 A162458 * A196092 A196089 A033359

Adjacent sequences: A097436 A097437 A097438 * A097440 A097441 A097442

Keyword

nonn

Author

Pierre CAMI, Aug 22 2004

Extensions

Data corrected by Amiram Eldar, Jul 17 2021

Status

approved