A340495 Records in first differences of A340494.

2, 3, 8, 33, 138, 563, 2268, 9093, 36398, 145623, 582528, 2330153, 9320658, 37282683, 149130788, 596523213, 2386092918, 9544371743, 38177487048, 152709948273, 610839793178, 2443359172803

Offset: 1

Author

Rémy Sigrist and N. J. A. Sloane, Jan 10 2021

Keywords

• nonn
• more

Links

• Rémy Sigrist, C program for A340495

Crossrefs

Cf. A340488, A340494.

Programs

C

See Links section.

Formula

The sequence a(n)-4*a(n-1) appears to be -5, -4, 1, 6, 11, 16, 21, 26, 31, 36, 41, 46, ... which is essentially 5*k+1 (k >= -1). The sequence itself appears to have g.f. =

x*(2*x-1)*(2*x^2+5*x-2)/((1-x)^2*(1-4*x)).