OFFSET
1,2
COMMENTS
May be regarded as table T(n,j) for j=1 to 2, where T(n,1)=n, T(n,2)=2*n+2 T(n,1)=number of carbon atoms in alkane hydrocarbons C_n H_{2n+2}, T(n,2)=number of hydrogen atoms in alkane hydrocarbons C_nH_{2n+2}.
LINKS
Arkadiusz Wesolowski, Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (0,2,0,-1).
FORMULA
G.f.: (2 + x)/(1 - x^2)^2. - Arkadiusz Wesolowski, Dec 28 2011
MATHEMATICA
a[n_] := If[OddQ[n], (n + 1)/2, n + 2]; Table[a[n], {n, 100}] (* Stefan Steinerberger, May 13 2006 *)
LinearRecurrence[{0, 2, 0, -1}, {1, 4, 2, 6}, 100] (* Harvey P. Dale, Sep 14 2016 *)
PROG
(PARI) a(n)=if(n%2, (n+1)/2, n+2) \\ Charles R Greathouse IV, Sep 02 2015
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Pierre CAMI, Sep 18 2004
EXTENSIONS
More terms from Stefan Steinerberger, May 13 2006
STATUS
approved