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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A349961 a(n) = Sum_{k=0..n} (2*n)^k. 1
 1, 3, 21, 259, 4681, 111111, 3257437, 113522235, 4581298449, 210027483919, 10778947368421, 612142982430915, 38108188628928601, 2580398988131886039, 188802050194014479853, 14843696896551724137931, 1247923426698972051309601, 111713733654631566667971615 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..17. FORMULA a(n) = ((2*n)^(n+1) - 1)/(2*n - 1). MATHEMATICA a[0] = 1; a[n_] := Sum[(2*n)^k, {k, 0, n}]; Array[a, 18, 0] (* Amiram Eldar, Dec 07 2021 *) PROG (PARI) a(n) = sum(k=0, n, (2*n)^k); (PARI) a(n) = ((2*n)^(n+1)-1)/(2*n-1); CROSSREFS Cf. A031973, A155956. Sequence in context: A317059 A262939 A232470 * A251573 A265002 A012131 Adjacent sequences: A349958 A349959 A349960 * A349962 A349963 A349964 KEYWORD nonn,easy AUTHOR Seiichi Manyama, Dec 07 2021 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 March 3 06:28 EST 2024. Contains 370499 sequences. (Running on oeis4.)