This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A226490 a(n) = n*(19*n-15)/2. 4
 0, 2, 23, 63, 122, 200, 297, 413, 548, 702, 875, 1067, 1278, 1508, 1757, 2025, 2312, 2618, 2943, 3287, 3650, 4032, 4433, 4853, 5292, 5750, 6227, 6723, 7238, 7772, 8325, 8897, 9488, 10098, 10727, 11375, 12042, 12728, 13433, 14157, 14900, 15662, 16443, 17243 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Sum of n-th hendecagonal number and n-th dodecagonal number. Sum of reciprocals of a(n), for n>0: 0.59314195720519963010713286193275... LINKS Bruno Berselli, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA G.f.: x*(2+17*x)/(1-x)^3. MATHEMATICA Table[n (19 n - 15)/2, {n, 0, 50}] CoefficientList[Series[x (2 + 17 x) / (1 - x)^3, {x, 0, 45}], x] (* Vincenzo Librandi, Aug 18 2013 *) LinearRecurrence[{3, -3, 1}, {0, 2, 23}, 50] (* Harvey P. Dale, Aug 17 2017 *) PROG (MAGMA) [n*(19*n-15)/2: n in [0..50]]; (MAGMA) I:=[0, 2, 23]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+Self(n-3): n in [1..45]]; // Vincenzo Librandi, Aug 18 2013 (PARI) a(n)=n*(19*n-15)/2 \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Cf. A051624, A051682. Cf. numbers of the form n*(n*k-k+4))/2, this sequence is the case k=19: see list in A226488. Sequence in context: A102385 A290226 A214596 * A217113 A042679 A209194 Adjacent sequences:  A226487 A226488 A226489 * A226491 A226492 A226493 KEYWORD nonn,easy AUTHOR Bruno Berselli, Jun 09 2013 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 18 10:49 EDT 2019. Contains 328147 sequences. (Running on oeis4.)