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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A070261 4th diagonal of triangle defined in A051537. 2
 4, 10, 2, 28, 40, 6, 70, 88, 12, 130, 154, 20, 208, 238, 30, 304, 340, 42, 418, 460, 56, 550, 598, 72, 700, 754, 90, 868, 928, 110, 1054, 1120, 132, 1258, 1330, 156, 1480, 1558, 182, 1720, 1804, 210, 1978, 2068, 240, 2254, 2350, 272, 2548, 2650, 306, 2860 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Colin Barker, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (0,0,3,0,0,-3,0,0,1). FORMULA a(n) = lcm(n + 3, n) / gcd(n + 3, n). From Colin Barker, Mar 27 2017: (Start) G.f.: 2*x*(2 + 5*x + x^2 + 8*x^3 + 5*x^4 - x^6 - x^7) / ((1 - x)^3*(1 + x + x^2)^3). a(n) = 3*a(n-3) - 3*a(n-6) + a(n-9) for n>9. (End) From Amiram Eldar, Oct 08 2023: (Start) Sum_{n>=1} 1/a(n) = 3/2. Sum_{n>=1} (-1)^n/a(n) = 22*log(2)/9 - 7/6. Sum_{k=1..n} a(k) ~ (19/81) * n^3. (End) MATHEMATICA Table[ LCM[i + 3, i] / GCD[i + 3, i], {i, 1, 60}] PROG (PARI) Vec(2*x*(2 + 5*x + x^2 + 8*x^3 + 5*x^4 - x^6 - x^7) / ((1 - x)^3*(1 + x + x^2)^3) + O(x^60)) \\ Colin Barker, Mar 27 2017 CROSSREFS Cf. A051537. Sequence in context: A337840 A349305 A244152 * A367029 A054048 A121512 Adjacent sequences: A070258 A070259 A070260 * A070262 A070263 A070264 KEYWORD nonn,easy AUTHOR Amarnath Murthy, May 09 2002 EXTENSIONS Edited by Robert G. Wilson v, May 10 2002 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 June 20 08:30 EDT 2024. Contains 373512 sequences. (Running on oeis4.)