A239674 Where records occur in A239656 (the first differences of sphenic numbers).

1, 2, 19, 498, 2114, 8351, 8381, 59704, 233890, 291963, 1119181, 1507131, 1839746, 9768399, 40844982, 94852115, 138032741, 443653568, 453853664, 2491818901

Offset

1,2

Links

Table of n, a(n) for n=1..20.

Formula

A239656(a(n)) = A239673(n).

Prog

(Haskell)
a239674 n = a239674_list !! (n-1)
-- See A239673 for definition of A239674_list.
(PARI) list(lim)=my(v=List(), t); forprime(p=2, (lim)^(1/3), forprime(q=p+1, sqrt(lim\p), t=p*q; forprime(r=q+1, lim\t, listput(v, t*r)))); vecsort(Vec(v)) ; \\ A007304
chk(lim) = my(v=list(lim), dv = vector(#v-1, k, v[k+1] - v[k]), r=0); for (i=1, #dv, if (dv[i] > r, r=dv[i]; print1(i, ", ")); ); \\ Michel Marcus, Sep 20 2023

Crossrefs

Cf. A007304, A085809, A239656, A239673.

Sequence in context: A332967 A120420 A350939 * A306457 A158099 A015204

Adjacent sequences: A239671 A239672 A239673 * A239675 A239676 A239677

Keyword

nonn,more

Author

Reinhard Zumkeller, Mar 23 2014

Extensions

a(12)-a(14) from Michel Marcus, Sep 20 2023

a(15)-a(20) from Amiram Eldar, May 19 2024

Status

approved