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A146951
Numbers that are congruent to 0 or 6 mod 10.
4
0, 6, 10, 16, 20, 26, 30, 36, 40, 46, 50, 56, 60, 66, 70, 76, 80, 86, 90, 96, 100, 106, 110, 116, 120, 126, 130, 136, 140, 146, 150, 156, 160, 166, 170, 176, 180, 186, 190, 196, 200, 206, 210, 216, 220, 226, 230, 236, 240, 246, 250, 256, 260, 266, 270, 276, 280
OFFSET
0,2
COMMENTS
Rank of terms of A061047 ending in with 0.
FORMULA
a(n) = Sum_{k>=0} A030308(n,k)*b(k) with b(0)=6 and b(k) = 5*2^k = A020714(k) for k > 0. - Philippe Deléham, Oct 18 2011
From Colin Barker, May 15 2012: (Start)
a(n) = 1/2 - (-1)^n/2 + 5*n.
a(n) = a(n-1) + a(n-2) - a(n-3).
G.f.: x*(6+4*x)/((1-x)^2*(1+x)). (End)
E.g.f.: 5*x*exp(x) + sinh(x). - Stefano Spezia, May 14 2021
Sum_{n>=1} (-1)^(n+1)/a(n) = log(5)/8 - sqrt(1-2/sqrt(5))*Pi/20 - log(phi)/(4*sqrt(5)), where phi is the golden ratio (A001622). - Amiram Eldar, Sep 15 2022
MATHEMATICA
CoefficientList[Series[x*(6+4*x)/((1-x)^2*(1+x)), {x, 0, 50}], x] (* Vincenzo Librandi, May 18 2012 *)
PROG
(Magma) I:=[0, 6, 10]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..50]]; // Vincenzo Librandi, May 18 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Nov 03 2008
EXTENSIONS
Replaced definition by a comment from Philippe Deléham, Oct 18 2011. Afer the change this becomes a list, but it is better to keep the offset as 0. - N. J. A. Sloane, Sep 08 2022
STATUS
approved