The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A334066 a(n) = (2n-1)!!*(Sum_{k=1..n}k/(2*k-1)). 1
 1, 5, 34, 298, 3207, 40947, 605076, 10157220, 190915965, 3971997585, 90613969110, 2249113016430, 60338869272675, 1739831420490975, 53656981894391400, 1762410972384203400, 61421841416041392825, 2263752327235180060125, 87970054921758957890250 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA a(n) = (2n-1)!!*(Sum_{k=1..n}k/(2*k-1)). Recurrence: a(n) = 2*a(n-1) + (2*n-3)^2*a(n-2) + (2*n-1)!!. EXAMPLE a(4)=298 since 1/1+2/3+3/5+4/7=298/105=298/(7!!). MATHEMATICA Table[Sum[k/(2*k-1), {k, 1, n}], {n, 1, 19}]*Table[Product[2*j-1, {j, 1, n}], {n, 1, 19}] FullSimplify[Table[(n/2 + HarmonicNumber[n - 1/2]/4 + Log[2]/2) * (2*n-1)!!, {n, 1, 20}]] (* Vaclav Kotesovec, Apr 14 2020 *) CROSSREFS Cf. A004041. Sequence in context: A284864 A208677 A259906 * A330649 A121323 A328488 Adjacent sequences:  A334063 A334064 A334065 * A334067 A334068 A334069 KEYWORD nonn,easy AUTHOR Greg Huber, Apr 13 2020 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 September 20 03:57 EDT 2020. Contains 337264 sequences. (Running on oeis4.)