A068510 a(n) = lcm(1,...,n) - (product of primes <= n).

0, 0, 0, 6, 30, 30, 210, 630, 2310, 2310, 25410, 25410, 330330, 330330, 330330, 690690, 11741730, 11741730, 223092870, 223092870, 223092870, 223092870, 5131136010, 5131136010, 26548051530, 26548051530, 80090340330, 80090340330

Offset: 1

Author

N. J. A. Sloane, Mar 21 2002

Keywords

• nonn
• easy

References

• Tenenbaum, G. (2015). Introduction to analytic and probabilistic number theory, 3rd ed., American Mathematical Soc. See page 22.

Links

• T. D. Noe, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A059794, A068511.

Programs

Maple

a[1] := 0:a[2] := 0:l := 2:p := 3:pp := 2:for i from 3 to 50 do l := ilcm(l,i): if(p=i) then pp := pp*p:p := nextprime(p):end if: a[i] := l-pp:end do:q := seq(a[j],j=1..50);

Mathematica

f[n_] := (LCM @@ Table[i, {i, n}] - Product[Prime[i], {i, PrimePi[n]}]); Table[f[n], {n, 30}]

Extensions

More terms from Sascha Kurz, Mar 23 2002