The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A064762 a(n) = 21*n^2. 5
 0, 21, 84, 189, 336, 525, 756, 1029, 1344, 1701, 2100, 2541, 3024, 3549, 4116, 4725, 5376, 6069, 6804, 7581, 8400, 9261, 10164, 11109, 12096, 13125, 14196, 15309, 16464, 17661, 18900, 20181, 21504, 22869, 24276, 25725, 27216, 28749 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Number of edges in a complete 7-partite graph of order 7n, K_n,n,n,n,n,n,n. LINKS Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) = 42*n+a(n-1)-21 for n>0, a(0)=0. - Vincenzo Librandi, Aug 07 2010 a(n) = 21*A000290(n) = 7*A033428(n) = 3*A033582(n). - Omar E. Pol, Jul 03 2014 a(n) = t(7*n) - 7*t(n), where t(i) = i*(i+k)/2 for any k. Special case (k=1): a(n) = A000217(7*n) - 7*A000217(n). - Bruno Berselli, Aug 31 2017 MATHEMATICA 21 Range[0, 50]^2 (* Wesley Ivan Hurt, Jul 04 2014 *) LinearRecurrence[{3, -3, 1}, {0, 21, 84}, 40] (* Harvey P. Dale, Jul 29 2019 *) PROG (Magma) [21*n^2 : n in [0..50]]; // Wesley Ivan Hurt, Jul 04 2014 (PARI) a(n)=21*n^2 \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Cf. A000217, A000290, A033428, A033581, A033583. Similar sequences are listed in A244630. Sequence in context: A195961 A190023 A071397 * A104676 A143244 A041856 Adjacent sequences: A064759 A064760 A064761 * A064763 A064764 A064765 KEYWORD nonn,easy AUTHOR Roberto E. Martinez II, Oct 18 2001 STATUS approved

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

Last modified November 29 06:00 EST 2022. Contains 358422 sequences. (Running on oeis4.)