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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A051844 Least common multiple of {2^k + 1, k=0..n}. 2
2, 6, 30, 90, 1530, 16830, 218790, 9407970, 2417848290, 137817352530, 28252557268650, 19296496614487950, 4650455684091595950, 12700394473254148539450, 41619192688853844763777650, 13775952780010622616810402150, 902834617343556174437903325704550 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..16.

FORMULA

a(n) = lcm(2, 3, 5, ..., 2^n + 1).

Product_{k=1..n} cyclotomic(2*k-2, 2). - Vladeta Jovovic, Apr 05 2004

EXAMPLE

a(3) = lcm(2, 3, 5) = 30.

MATHEMATICA

Module[{nn=20, c}, c=Table[2^n+1, {n, 0, nn}]; Table[LCM@@Take[c, n], {n, nn}]] (* Harvey P. Dale, Aug 04 2017 *)

PROG

(PARI) a(n) = {ret = 1; for (k=0, n, ret = lcm(ret, 2^k+1)); return(ret); } \\ Michel Marcus, May 24 2013

CROSSREFS

Cf. A034268.

Cf. A019320.

Sequence in context: A290760 A088857 A099081 * A335396 A034501 A203461

Adjacent sequences:  A051841 A051842 A051843 * A051845 A051846 A051847

KEYWORD

nonn

AUTHOR

Jeffrey Shallit, Apr 20 2000

EXTENSIONS

More terms from Harvey P. Dale, Aug 04 2017

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 10 19:52 EDT 2020. Contains 336381 sequences. (Running on oeis4.)