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A034268 Least common multiple of {2^k - 1, k=1..n}. 4
1, 3, 21, 105, 3255, 9765, 1240155, 21082635, 1539032355, 16929355905, 34654391537535, 450507089987955, 3690103574091339405, 158674453685927594415, 23959842506575066756665, 6157679524189792156462905, 807093212915080247739749421255 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..100

MathOverflow, Do we know any bound on lcm(2^1-1, 2^2-1, ..., 2^n-1)?

FORMULA

lcm(1, 3, 7, ..., 2^n - 1).

Product_{k=1..n} Phi_k(2), where Phi_n(2) is n-th cyclotomic polynomial at x=2 (cf. A019320). - Vladeta Jovovic, Jan 20 2002

EXAMPLE

a(3) = lcm(1,3,7) = 21.

MAPLE

a:= proc(n) option remember; `if`(n=1, 1, ilcm(a(n-1), 2^n-1)) end:

seq(a(n), n=1..20);  # Alois P. Heinz, Oct 16 2011

MATHEMATICA

Table[LCM @@ (2^Range[n] - 1), {n, 1, 20}] (* Jean-Fran├žois Alcover, Apr 02 2015 *)

PROG

(PARI) A034268(n) = {local(r); r=1; for(k=1, n, r=lcm(r, 2^k-1)); r} \\ Michael B. Porter, Mar 02 2010

CROSSREFS

Cf. A051844.

Cf. A019320.

Sequence in context: A076207 A134057 A128281 * A140451 A054147 A233582

Adjacent sequences:  A034265 A034266 A034267 * A034269 A034270 A034271

KEYWORD

nonn

AUTHOR

Jeffrey Shallit, Apr 20 2000

STATUS

approved

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Last modified January 26 23:05 EST 2020. Contains 331289 sequences. (Running on oeis4.)