This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A139277 a(n) = n*(8*n+5). 7
 0, 13, 42, 87, 148, 225, 318, 427, 552, 693, 850, 1023, 1212, 1417, 1638, 1875, 2128, 2397, 2682, 2983, 3300, 3633, 3982, 4347, 4728, 5125, 5538, 5967, 6412, 6873, 7350, 7843, 8352, 8877, 9418, 9975, 10548, 11137, 11742, 12363, 13000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Sequence found by reading the line from 0, in the direction 0, 13, ..., in the square spiral whose vertices are the triangular numbers A000217. Opposite numbers to the members of A139273 in the same spiral. LINKS Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) = 8*n^2 + 5n. Sequences of the form a(n) = 8*n^2 + c*n have generating functions x{c+8+(8-c)x} / (1-x)^3 and recurrence a(n) = 3a(n-1) - 3a(n-2) + a(n-3). The inverse binomial transform is 0, c+8, 16, 0, 0, ... (0 continued). This applies to A139271-A139278, positive or negative c. - R. J. Mathar, May 12 2008 a(n) = 16*n + a(n-1) - 3 for n>0, a(0)=0. - Vincenzo Librandi, Aug 03 2010 MATHEMATICA Table[n (8 n + 5), {n, 0, 50}] (* Bruno Berselli, Aug 22 2018 *) LinearRecurrence[{3, -3, 1}, {0, 13, 42}, 50] (* Harvey P. Dale, Dec 04 2018 *) PROG (PARI) a(n)=n*(8*n+5) \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Cf. A000217, A014634, A014635, A033585, A033586, A033587, A035008, A051870, A069129, A085250, A139272, A139273, A139274, A139275, A139276, A139278, A139279, A139280, A139281, A139282. Sequence in context: A002673 A081301 A159527 * A162265 A233298 A243028 Adjacent sequences:  A139274 A139275 A139276 * A139278 A139279 A139280 KEYWORD nonn,easy AUTHOR Omar E. Pol, Apr 26 2008 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 16 18:03 EDT 2019. Contains 328102 sequences. (Running on oeis4.)