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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A212428 a(n) = 18*n + A000217(n-1). 3
 0, 18, 37, 57, 78, 100, 123, 147, 172, 198, 225, 253, 282, 312, 343, 375, 408, 442, 477, 513, 550, 588, 627, 667, 708, 750, 793, 837, 882, 928, 975, 1023, 1072, 1122, 1173, 1225, 1278, 1332, 1387, 1443, 1500, 1558, 1617, 1677, 1738, 1800, 1863, 1927, 1992 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Generalization: T(n,i) = A000217(i-1+n) - A000217(i-1) = i*n + A000217(n-1) (corrected by Zak Seidov, Jun 21 2012); in this case is i=18. For i = 11..16, Milan Janjic observed that if we define f(n,b,i) = Sum_{k=0..n-b} binomial(n,k)*Stirling1(n-k,b)*Product_{j=0..k-1} (-i - j), then T(n-1,i) = -f(n,n-1,i) for n >= 1. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) = (17+n)*(18+n)/2 - 17*18/2 = 18*n + (n-1)*n/2 = n*(n+35)/2. G.f.: x*(18-17*x)/(1-x)^3. - Bruno Berselli, Jun 21 2012 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Vincenzo Librandi, Jul 10 2012 a(n) = 18n - floor(n/2) + floor(n^2/2). - Wesley Ivan Hurt, Jun 15 2013 From Amiram Eldar, Jan 11 2021: (Start) Sum_{n>=1} 1/a(n) = 2*A001008(35)/(35*A002805(35)) = 54437269998109/229732925058000. Sum_{n>=1} (-1)^(n+1)/a(n) = 4*log(2)/35 - 102126365345729/2527062175638000. (End) MATHEMATICA Table[-18 (18 - 1)/2 + (18 + n) (17 + n)/2, {n, 0, 100}] PROG (Magma) [n*(n+35)/2: n in [0..48]]; // Bruno Berselli, Jun 21 2012 (PARI) a(n)=n*(n+35)/2 \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Cf. A000217, A000096, A001008, A002805, A055998-A056000, A056115, A056119, A056121, A056126, A051942, A101859, A132754-A132758, A212427. Sequence in context: A198802 A041638 A041636 * A195147 A198276 A041640 Adjacent sequences: A212425 A212426 A212427 * A212429 A212430 A212431 KEYWORD nonn,easy AUTHOR Jesse Han, May 16 2012 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 September 29 16:37 EDT 2023. Contains 365773 sequences. (Running on oeis4.)