A177680 Numbers n such that 6n and 12n are both the average of twin prime pairs.

1, 5, 110, 135, 355, 425, 555, 565, 975, 1045, 1755, 5530, 6935, 7355, 8925, 9240, 9555, 10640, 10850, 11730, 11830, 12045, 12350, 12460, 13130, 13445, 13655, 14590, 15540, 17050, 19245, 20795, 22330, 22825, 26070, 26910, 28075, 30585, 30805

Offset: 1

Author

Juri-Stepan Gerasimov, May 10 2010

Keywords

• nonn

Comments

Conjecture: all terms but the first term are multiples of 5. - Harvey P. Dale, Sep 26 2017

Examples

			a(1)=1 because 6*1-1=5, 6*1+1=7, 12*1-1=11 and 12*1+1=13 are all twin primes.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A014574.

Programs

Mathematica

Select[Range[31000],AllTrue[Flatten[{6*#+{1,-1},12*#+{1,-1}}],PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 26 2017 *)

Formula

a(n)=A066388(n)/6.

Extensions

Corrected (13590 removed, 13655 and 14590 inserted, 22725 replaced by 22825) by R. J. Mathar, May 15 2010