A130480 - OEIS

A130480

a(n) = lcm(b(0),b(1),b(2),...,b(n)), where b(m) = A130479(m).

1, 1, 2, 6, 24, 120, 240, 1680, 13440, 120960, 241920, 2661120, 10644480, 138378240, 276756480, 4151347200, 66421555200, 1129166438400, 2258332876800, 42908324659200, 171633298636800, 3604299271372800, 7208598542745600

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

Table of n, a(n) for n=0..22.

EXAMPLE

a(6) = lcm(b(0),b(1),b(2),b(3),b(4),b(5),b(6)) = lcm(1,1,2,3,8,5,16) = 240. 6!! = 6*4*2 = 48 divides 240.

MAPLE

A130480 := proc(nmax) local a, n, df, k, f, p, l, b; a := [1, 1] ; while nops(a)< nmax do n := nops(a) ; df := ifactors(doublefactorial(n))[2] ; l := ilcm(op(a)) ; k := 1 ; for f in df do p := op(1, f)^op(2, f) ; if l mod p <> 0 then k := k*p ; fi; od: a := [op(a), k] ; od; b := [] ; for i from 1 to nops(a) do b := [op(b), ilcm(op(1..i, a))] ; od: RETURN(b) ; end: A130480(30) ; # R. J. Mathar, Oct 16 2007

CROSSREFS

Cf. A130479.

Sequence in context: A279435 A263699 A083267 * A000804 A048631 A263700

Adjacent sequences: A130477 A130478 A130479 * A130481 A130482 A130483

KEYWORD

nonn

AUTHOR

Leroy Quet, May 29 2007

EXTENSIONS

More terms from R. J. Mathar, Oct 16 2007

STATUS

approved