A138278 Sequence identical to its third differences in absolute values.

1, 2, 4, 8, 16, 24, 40, 80, 120, 200, 400, 600, 1000, 2000, 3000, 5000, 10000, 15000, 25000, 50000, 75000, 125000, 250000, 375000, 625000, 1250000, 1875000, 3125000, 6250000, 9375000, 15625000, 31250000, 46875000, 78125000, 156250000, 234375000, 390625000

Offset: 0

Author

Paul Curtz, May 06 2008

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (0,0,5).

Crossrefs

Cf. A131292, A131665, A132158, A132418, A132658.

Programs

Mathematica

Join[{1,2,4},LinearRecurrence[{0,0,5},{8,16,24},40]] (* Harvey P. Dale, Dec 08 2011 *)

Formula

From R. J. Mathar, Mar 23 2010: (Start)

a(n) = 5*a(n-3), n>5.

G.f.: (3*x^3+6*x^4+4*x^5+1+2*x+4*x^2)/(1-5*x^3). (End)

Sum_{n>=0} 1/a(n) = 391/192. - Amiram Eldar, Jan 14 2024

Extensions

Edited by Charles R Greathouse IV, Mar 18 2010

More terms from Harvey P. Dale, Dec 08 2011