A172180 The absolute value of n-th prime of the form 3*n-+1 minus n-th nonprime of the form 3*n-+1.

1, 1, 1, 1, 1, 1, 1, 1, 4, 5, 9, 9, 9, 12, 15, 19, 17, 21, 22, 23, 27, 28, 33, 39, 39, 39, 42, 41, 43, 53, 55, 60, 59, 67, 66, 71, 75, 76, 81, 85, 86, 93, 93, 93, 93, 101, 111, 112, 113, 115, 120, 120, 129, 133, 138, 141, 141, 144, 147, 147, 153, 165, 168, 168, 171, 183, 185

Offset: 1

Author

Juri-Stepan Gerasimov, Jan 28 2010

Keywords

• nonn

Crossrefs

Cf. A045344, A171993.

Programs

Maple

a(1)=abs(2-1)=1, a(2)=abs(5-4)=1, a(3)=abs(7-8)=1, a(4)=abs(11-10)=1, a(5)=abs(13-14)=1, a(6)=abs(17-16)=1, a(7)=abs(19-20)=1, a(8)=abs(23-22)=1, a(9)=abs(29-25)=4.

Formula

a(n)=abs(A045344(n)-A171993(n)).

Extensions

Corrected (28 inserted, a third 39 inserted etc.) by R. J. Mathar, May 19 2010