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A046698 a(0) = 0, a(1) = 1, a(n) = a(a(n-1)) + a(a(n-2)) if n > 1. 17
0, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Partial sums are A004275. Binomial transform is A048492, starting with 0. - Paul Barry, Feb 28 2003

REFERENCES

Sequence proposed by Reg Allenby.

O. Deveci, Y. Akuzum, E. Karaduman, O. Erdag, The Cyclic Groups via Bezout Matrices, Journal of Mathematics Research, Vol. 7, No. 2, 2015, pp. 34-41.

LINKS

Table of n, a(n) for n=0..101.

Ömür Deveci, Zafer Adıgüzel, Taha Doğan, On the Generalized Fibonacci-circulant-Hurwitz numbers, Notes on Number Theory and Discrete Mathematics (2020) Vol. 26, No. 1, 179-190.

Eric Weisstein's World of Mathematics, Fibonacci n-Step Number

FORMULA

G.f.: x*(1+x^2)/(1-x). - Paul Barry, Feb 28 2003

a(n) = 2*((n+2) mod (n+1))-(C(n^2,n+2) mod 2)-(C((n+1)^2,n+3) mod 2). - Paolo P. Lava, Sep 03 2007

MAPLE

P:=proc(n) local a, i; for i from 0 by 1 to n do a:=2*((i+2) mod (i+1))-(binomial((i)^2, i+2) mod 2)-(binomial((i+1)^2, i+3) mod 2); print(a); od; end: P(100); # Paolo P. Lava, Sep 03 2007

MATHEMATICA

CoefficientList[Series[x (1 + x^2)/(1 - x), {x, 0, 104}], x] (* or *)

Nest[Append[#, #[[#[[-1]] + 1]] + #[[#[[-2]] + 1 ]]] &, {0, 1}, 105] (* Michael De Vlieger, Jul 31 2020 *)

PROG

(PARI) a(n)=(n>0)+(n>2)

CROSSREFS

Sequence in context: A084100 A329683 A130130 * A007395 A036453 A040000

Adjacent sequences:  A046695 A046696 A046697 * A046699 A046700 A046701

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, R. K. Guy

STATUS

approved

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Last modified July 31 03:28 EDT 2021. Contains 346367 sequences. (Running on oeis4.)