A025537 - OEIS

A025537

a(n) = (1/s(1) + 1/s(2) + ... + 1/s(n+1)) * LCM{1, 2, ..., n}, where s(k) = LCM{1,2,...,k}/k = A002944(k).

1, 2, 5, 17, 35, 181, 182, 1278, 2559, 7687, 7688, 84580, 84581, 1099567, 1099582, 1099590, 2199181, 37386095, 37386096, 710335844, 710335865, 710335887, 710335888, 16337725448, 16337725453, 81688627291, 81688627300, 245065881928, 245065881929

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..28.

FORMULA

a(n) = A003418(n) * Sum_{k=1..n+1} 1/A002944(k). - Sean A. Irvine, Sep 04 2019

EXAMPLE

n=4: LCM{1,2,3,4} = 12, so a(4) = 12*(1/1 + 1/1 + 1/2 + 1/3 + 1/12) = 12*35/12 = 35. - N. J. A. Sloane, Sep 04 2019

PROG

(PARI) s(n) = lcm([1..n])/n; \\ A002944

a(n) = lcm([1..n])*sum(k=1, n+1, 1/s(k)); \\ Michel Marcus, Sep 04 2019

CROSSREFS

Cf. A003418, A002944, A025527.

Sequence in context: A075345 A045705 A125822 * A245784 A247068 A028916

Adjacent sequences: A025534 A025535 A025536 * A025538 A025539 A025540

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Name improved by Sean A. Irvine, Sep 04 2019 and N. J. A. Sloane, Sep 04 2019

STATUS

approved