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

Author

Reinhard Zumkeller, Mar 23 2014

Keywords

• nonn
• more

Crossrefs

Cf. A007304, A085809, A239656, A239673.

Programs

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

Formula

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

Extensions

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

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