A194350 Numbers covering A000027: a(n) = (1, 1, 2, 5) * A011557(n).

1, 1, 2, 5, 10, 10, 20, 50, 100, 100, 200, 500, 1000, 1000, 2000, 5000, 10000, 10000, 20000, 50000, 100000, 100000, 200000, 500000, 1000000, 1000000, 2000000, 5000000, 10000000, 10000000, 20000000, 50000000

Offset

1,3

Comments

3=1+2, 4=1+1+2, 6=1+5, 7=2+5, 8=1+2+5, 9=1+1+2+5, 11=1+10, 12=2+10, 13=1+2+10.

a(n) is used only once. Like weights.

Links

Table of n, a(n) for n=1..32.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,10).

Formula

a(1)=1, a(2)=1, a(3)=2, a(4)=5, a(n)=10*a(n-4). G.f.: x*(1+x+2*x^2+5*x^3)/(1-10*x^4). [Colin Barker, Jan 25 2012]

Mathematica

LinearRecurrence[{0, 0, 0, 10}, {1, 1, 2, 5}, 40] (* Harvey P. Dale, Jan 21 2019 *)

Prog

(PARI) a(n)=10^(n\4)*[1/2, 1, 1, 2][n%4+1] \\ Charles R Greathouse IV, Dec 21 2011

Crossrefs

Sequence in context: A078310 A359487 A138848 * A182179 A123466 A144793

Adjacent sequences: A194347 A194348 A194349 * A194351 A194352 A194353

Keyword

nonn,easy

Author

Paul Curtz, Aug 22 2011

Status

approved