A163628 Integers such that the two adjacent integers are a prime and three times a prime.

8, 10, 14, 16, 20, 22, 32, 38, 40, 52, 58, 68, 70, 88, 110, 112, 128, 130, 140, 158, 178, 182, 200, 212, 238, 250, 268, 292, 308, 310, 338, 380, 382, 410, 418, 448, 488, 490, 500, 502, 520, 542, 572, 578, 592, 598, 632, 682, 700, 718, 752, 770, 772, 788, 808

Offset: 1

Author

Juri-Stepan Gerasimov, Aug 02 2009

Keywords

• nonn

Comments

Union[3*A023208 + 1, 3*A088878 - 1]. [Zak Seidov, Aug 07 2009]

Examples

			a(1)=8 which lies between 7=A000040(4) and 9 = A001748(2).
a(2)=10 which lies between 9=A001748(2) and 11 = A000040(5).
		

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A163492.

Programs

Mathematica

n = 1; A023208 = {}; Do[If[PrimeQ[(Prime[k] - 2 n)/(2 n + 1)], AppendTo[A023208, (Prime[k] - 2 n)/(2 n + 1)]], {k, 1, 1000}]; A023208;
A088878 = {}; Do[p = Prime[n]; If[PrimeQ[3*p - 2], AppendTo[A088878, p]], {n, 5!}]; A088878; Union[3*A023208 + 1, 3*A088878 - 1] (* G. C. Greubel, Jul 30 2017 *)

Extensions

Many terms like 44, 46, 62 etc. removed by R. J. Mathar, Aug 06 2009