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A106706 a(0) = 19; for n>0, successively subtract 5, subtract 3 and double. 1
19, 14, 11, 22, 17, 14, 28, 23, 20, 40, 35, 32, 64, 59, 56, 112, 107, 104, 208, 203, 200, 400, 395, 392, 784, 779, 776, 1552, 1547, 1544, 3088, 3083, 3080, 6160, 6155, 6152, 12304, 12299, 12296, 24592, 24587, 24584, 49168, 49163, 49160, 98320, 98315, 98312, 196624 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Suggested by a test found on the Internet.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

Jeffrey N. Shaumeyer, Bearcastle Blog, One Post, Two ... [Via Internet Archive Wayback-Machine]

Index entries for linear recurrences with constant coefficients, signature (0,0,3,0,0,-2).

FORMULA

G.f.: (19 + 14*x + 11*x^2 - 35*x^3 - 25*x^4 - 19*x^5)/((1 - 2*x^3)*(1 - x^3)).

a(3n) = 3*2^n+16, a(3n+1) = 3*2^n+11, a(3n+2) = 3*2^n+8.

MAPLE

f:=proc(n) option remember; if n=0 then RETURN(19); fi; if n mod 3 = 1 then RETURN(f(n-1)-5); elif n mod 3 = 2 then RETURN(f(n-1)-3); else RETURN(2*f(n-1)); fi; end;

MATHEMATICA

nxt[{b_, c_, d_}]:={d-5, d-8, 2d-16}; Join[{19}, Flatten[NestList[nxt, {14, 11, 22}, 20]]] (* Harvey P. Dale, Dec 01 2019 *)

PROG

(PARI) a(n)=3*2^(n\3)+[16, 11, 8][n%3+1]  \\ M. F. Hasler, Nov 16 2010

(Magma) I:=[19, 14, 11, 22, 17, 14]; [n le 6 select I[n] else 3*Self(n-3) - 2*Self(n-6): n in [1..61]]; // G. C. Greubel, Sep 09 2021

(Sage)

def p(n): return 0 if (n%3==0) else 5 if (n%3==1) else 8

def a(n, b): return 2^(n//3)*(b-16) + 16 - p(n)

[a(n, 19) for n in (0..60)] # G. C. Greubel, Sep 09 2021

CROSSREFS

Sequence in context: A177923 A155848 A088399 * A291427 A099939 A269231

Adjacent sequences:  A106703 A106704 A106705 * A106707 A106708 A106709

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, based on correspondence with Jeffrey N. Shaumeyer, Apr 23 2006

STATUS

approved

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Last modified October 6 02:32 EDT 2022. Contains 357261 sequences. (Running on oeis4.)