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

Offset: 0

Author

Clark Kimberling

Keywords

• nonn

Examples

			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
		

Crossrefs

Cf. A003418, A002944, A025527.

Programs

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

Formula

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

Extensions

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