A173237 Alternate k and 10k for each k.

1, 10, 2, 20, 3, 30, 4, 40, 5, 50, 6, 60, 7, 70, 8, 80, 9, 90, 10, 100, 11, 110, 12, 120, 13, 130, 14, 140, 15, 150, 16, 160, 17, 170, 18, 180, 19, 190, 20, 200, 21, 210, 22, 220, 23, 230, 24, 240, 25, 250, 26, 260, 27, 270, 28, 280, 29, 290, 30, 300, 31, 310, 32, 320, 33

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (0,2,0,-1).

Formula

G.f.: x*(1+10*x) / ( (x-1)^2*(1+x)^2 ). - R. J. Mathar, Jun 18 2014

Mathematica

LinearRecurrence[{0, 2, 0, -1}, {1, 10, 2, 20}, 80] (* Harvey P. Dale, Dec 28 2025 *)
(* Alternative: *)
{#, 10#}&/@Range[40]//Flatten (* Harvey P. Dale, Dec 28 2025 *)

Crossrefs

Cf. A008592, A101233.

Sequence in context: A228276 A040099 A330365 * A319154 A339138 A086068

Adjacent sequences: A173234 A173235 A173236 * A173238 A173239 A173240

Keyword

nonn,easy,changed

Author

Mark Dols, Feb 13 2010

Status

approved