This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A259079 Octagonal numbers (A000567) that are other octagonal numbers divided by 2. 2
 280, 373212840, 497012764340408, 661878856450449219400, 881433339438556519000044120, 1173817118196415977287174306335208, 1563188689740940473437573487667885475320, 2081720262768492984525248323578863263574296200 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Intersection of A000567 and A033579 (even octogonal numbers divided by 2). - Michel Marcus, Jun 20 2015 LINKS Colin Barker, Table of n, a(n) for n = 1..163 Index entries for linear recurrences with constant coefficients, signature (1331715,-1331715,1). FORMULA G.f.: -8*x*(x^2+41580*x+35) / ((x-1)*(x^2-1331714*x+1)). EXAMPLE 280 is in the sequence because 280 is the 10th octagonal number, and 2*280 is the 14th octagonal number. MATHEMATICA LinearRecurrence[{1331715, -1331715, 1}, {280, 373212840, 497012764340408}, 20] (* Harvey P. Dale, Dec 04 2015 *) PROG (PARI) Vec(-8*x*(x^2+41580*x+35)/((x-1)*(x^2-1331714*x+1)) + O(x^20)) CROSSREFS Cf. A000567, A075528, A107736, A259078. Sequence in context: A255498 A091034 A294165 * A296506 A308456 A175145 Adjacent sequences:  A259076 A259077 A259078 * A259080 A259081 A259082 KEYWORD nonn,easy AUTHOR Colin Barker, Jun 18 2015 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 December 14 22:42 EST 2019. Contains 329987 sequences. (Running on oeis4.)