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 A025558 a(n) = (n/(n+1)) * lcm(1,2,...,n+1). 4
 1, 4, 9, 48, 50, 360, 735, 2240, 2268, 25200, 25410, 332640, 334620, 336336, 675675, 11531520, 11571560, 220540320, 221152932, 221707200, 222211080, 5121436320, 5131136010, 25700298624, 25741485000, 77338861600, 77445096300, 2248776129600, 2251453244040 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = (1/1 + 1/3 + 1/6 + ... + 1/C(n+1,2))*lcm(1,3,6,...,binomial(n+1,2)) = 2n/(n+1) * lcm(1,3,6,...,binomial(n+1,2)). a(n+1) = a(n) * ((n+1)^2)/(n * ((n+2)/p) ), where p = n+2 if n+2 is prime, p = q if n+2 = q^k (q is prime, k>1), or p = 1 if n+2 is not a prime or a prime power. - Scott C. Macfarlan (scottmacfarlan(AT)covance.com), Jan 08 2004 LINKS FORMULA a(n) = n * A002944(n+1) = (n/(n+1)) * A003418(n+1). MAPLE a:= n-> (n/(n+1)) * ilcm(\$1..n+1): seq(a(n), n=1..29);  # Alois P. Heinz, Mar 07 2022 MATHEMATICA Table[n/(n+1) LCM@@Range[n+1], {n, 30}]  (* Harvey P. Dale, Apr 02 2011 *) PROG (PARI) a(n) = n*lcm([1..n+1])/(n+1); \\ Michel Marcus, Mar 07 2022 CROSSREFS Cf. A002944, A003418. Sequence in context: A197970 A048892 A108849 * A298986 A103933 A256880 Adjacent sequences:  A025555 A025556 A025557 * A025559 A025560 A025561 KEYWORD nonn AUTHOR EXTENSIONS Entry revised by N. J. A. Sloane, Nov 12 2004 STATUS approved

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Last modified May 27 11:47 EDT 2022. Contains 354097 sequences. (Running on oeis4.)