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A068510
a(n) = lcm(1,...,n) - (product of primes <= n).
2
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
1,4
REFERENCES
Tenenbaum, G. (2015). Introduction to analytic and probabilistic number theory, 3rd ed., American Mathematical Soc. See page 22.
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}]
CROSSREFS
Sequence in context: A287733 A066197 A078638 * A147798 A351226 A351228
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Mar 21 2002
EXTENSIONS
More terms from Sascha Kurz, Mar 23 2002
STATUS
approved