A239673 Record values in A239656 (the first differences of sphenic numbers).

12, 24, 27, 28, 33, 35, 43, 44, 46, 48, 50, 52, 60, 65, 70, 72, 79, 82, 92, 98

Offset: 1

Author

Reinhard Zumkeller, Mar 23 2014

Keywords

• nonn
• more

Crossrefs

Cf. A007304, A005250, A215231, A239656, A239674.

Programs

Haskell

a239673 n = a239673_list !! (n-1)
(a239673_list, a239674_list) = unzip $ (12, 1) : f 1 12 a239656_list where
   f i v (q:qs) | q > v = (q, i) : f (i + 1) q qs
                | otherwise = f (i + 1) v qs
-- Reinhard Zumkeller, Mar 23 2014

PARI

lista(kmax) = {my(k1 = 30, d, dm = 0); forcomposite(k2 = k1 + 1, kmax, if(factor(k2)[,2] == [1,1,1]~, d = k2 - k1; if(d > dm, dm = d; print1(d, ", ")); k1 = k2));} \\ Amiram Eldar, May 19 2024

Formula

a(n) = A239656(A239674(n)).

Extensions

a(12)-a(20) from Amiram Eldar, May 19 2024