A141495 a(n) = 3*a(n-1) for n>2; a(0)=1, a(1)=3, a(2)=7.

1, 3, 7, 21, 63, 189, 567, 1701, 5103, 15309, 45927, 137781, 413343, 1240029, 3720087, 11160261, 33480783, 100442349, 301327047, 903981141, 2711943423, 8135830269, 24407490807, 73222472421, 219667417263, 659002251789

Offset: 0

Author

Roger L. Bagula, Aug 10 2008

Keywords

• nonn
• easy

Comments

A sequence of the form: a(0)=1, a(1)=prime(m), a(2)=prime(m+2), a(n)=a(1)*a(n-1).

a(n) is divisible by 7 for n>1. - Colin Barker, Jan 09 2014

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (3).

Crossrefs

Essentially the same as A005032 and A084215. For other examples see A141496, etc.

Programs

Mathematica

a[0] = 1; a[1] = 3; a[2] = 7; a[n_] := a[n] = a[1]*a[n - 1]; Table[a[n], {n, 0, 30}]
Join[{1,3},NestList[3#&,7,30]] (* Harvey P. Dale, Aug 05 2024 *)

Formula

a(n) = A082541(n-1), n>1. - R. J. Mathar, Aug 27 2008

a(n) = 7*3^(n-2) for n>1. a(n)=3*a(n-1) for n>2. G.f.: (2*x^2-1) / (3*x-1). - Colin Barker, Jan 09 2014

Extensions

Edited by N. J. A. Sloane, Aug 16 2008