A138996 First differences of Frobenius numbers for 5 successive numbers A138985.

1, 1, 1, 7, 2, 2, 2, 12, 3, 3, 3, 17, 4, 4, 4, 22, 5, 5, 5, 27, 6, 6, 6, 32, 7, 7, 7, 37, 8, 8, 8, 42, 9, 9, 9, 47, 10, 10, 10, 52, 11, 11, 11, 57, 12, 12, 12, 62, 13, 13, 13, 67, 14, 14, 14, 72, 15, 15, 15, 77, 16, 16, 16, 82, 17, 17, 17, 87, 18, 18, 18, 92, 19, 19, 19, 97, 20, 20, 20

Offset: 1

Author

Artur Jasinski, Apr 05 2008

Keywords

• nonn
• easy

Comments

For first differences of Frobenius numbers for 2 successive numbers see A005843

For first differences of Frobenius numbers for 3 successive numbers see A014682

For first differences of Frobenius numbers for 4 successive numbers see A138995

For first differences of Frobenius numbers for 5 successive numbers see A138996

For first differences of Frobenius numbers for 6 successive numbers see A138997

For first differences of Frobenius numbers for 7 successive numbers see A138998

For first differences of Frobenius numbers for 8 successive numbers see A138999

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (0,0,0,2,0,0,0,-1).

Crossrefs

Cf. A028387, A037165, A079326, A138985, A138986, A138987, A138988, A138989, A138990, A138991, A138992, A138993, A138994, A138995, A138996, A138997, A138998, A138999.

Programs

Mathematica

a = {}; Do[AppendTo[a, FrobeniusNumber[{n + 1, n + 2, n + 3, n + 4, n + 5}]], {n, 1, 100}]; Differences[a]
LinearRecurrence[{0, 0, 0, 2, 0, 0, 0, -1}, {1, 1, 1, 7, 2, 2, 2,
  12}, 50] (* G. C. Greubel, Feb 18 2017 *)

PARI

x='x+O('x^50); Vec(-x*(2*x^7-7*x^3-x^2-x-1) / ((x-1)^2*(x+1)^2*(x^2+1)^2)) \\ G. C. Greubel, Feb 18 2017

Formula

a(n) = A138985(n+1) - A138985(n).

a(n) = 2*a(n-4) - a(n-8). - R. J. Mathar, Apr 20 2008

a(n) = -(1/4)*mod(n,4)*x(4+mod(n,4))+(1/4)*n*x(4+mod(n,4))+x(mod(n,4))-(1/4)*n*x(mod(n,4))+(1/4)*mod(n,4)*x(mod(n,4)). - Alexander R. Povolotsky, Apr 20 2008

G.f.: -x*(2*x^7-7*x^3-x^2-x-1) / ((x-1)^2*(x+1)^2*(x^2+1)^2). - Colin Barker, Dec 13 2012