A097926 Number of (n,4) Freiman-Wyner sequences.

18, 36, 70, 134, 258, 498, 960, 1850, 3566, 6874, 13250, 25540, 49230, 94894, 182914, 352578, 679616, 1310002, 2525110, 4867306, 9382034, 18084452, 34858902, 67192694, 129518082, 249654130, 481223808, 927588714, 1787984734, 3446451386

Offset

5,1

Comments

"The values for n <= 4 are straightforward."

References

I. F. Blake, The enumeration of certain run length sequences, Information and Control, 55 (1982), 222-237.

Links

Table of n, a(n) for n=5..34.

Index entries for linear recurrences with constant coefficients, signature (1,1,1,1).

Formula

a(n) = 2a(n-1) - a(n-k-1), k=4, n >= 2k+2. - R. J. Mathar, Oct 31 2006

G.f.: -2*(5*x^3+8*x^2+9*x+9)*x^5/(x^4+x^3+x^2+x-1) = -10*x^4-6*x^3-2*x^2-2+(-2*x^3-2+2*x)/(x^4+x^3+x^2+x-1). - R. J. Mathar, Nov 18 2007

Maple

A097926 := proc(nmax) local a, n, k; k := 4 ; a := [18, 36, 70, 134, 258] ; while nops(a) < nmax do n := nops(a)+k+1 ; a := [op(a), 2*op(n-1-k, a)-op(n-2*k-1, a) ] ; od ; end: nmax := 30 ; a := A097926(nmax) ; for i from 1 to nmax do printf("%d, ", op(i, a)) ; od: # R. J. Mathar, Oct 31 2006

Mathematica

LinearRecurrence[{1, 1, 1, 1}, {18, 36, 70, 134}, 30] (* Harvey P. Dale, Jun 06 2022 *)

Crossrefs

Cf. A006355, A097925.

Sequence in context: A131766 A154575 A344199 * A087967 A070224 A083211

Adjacent sequences: A097923 A097924 A097925 * A097927 A097928 A097929

Keyword

nonn

Author

N. J. A. Sloane, Sep 05 2004

Extensions

Corrected and extended by R. J. Mathar, Oct 31 2006

Status

approved