A348882 Numbers that are expressible as the product of the number of distinct prime factors of preceding integers.

16, 48, 72, 96, 144, 432, 576, 1296, 2592, 5184, 20736, 32805, 221184, 1555200, 11197440, 55987200, 95551488, 268738560, 302330880, 382205952, 524880000, 671846400, 6718464000, 34012224000, 155520000000, 403107840000, 6856864358400, 107495424000000, 110075314176000

Offset

1,1

Links

Table of n, a(n) for n=1..29.

Example

The number of distinct prime factors of the numbers 15, 14, 13, 12, 11, 10 are respectively 2, 2, 1, 2, 1, 2 and 2*2*1*2*1*2 = 16, hence 16 is a term.

Mathematica

om[n_] := om[n] = PrimeNu[n]; q[n_] := Module[{m = n, k = n - 1}, While[k > 1 && Divisible[m, om[k]], m /= om[k]; k--]; m == 1]; Select[Range[2, 10^6], q] (* Amiram Eldar, Nov 02 2021 *)

Crossrefs

Cf. A001221, A000961, A007774, A033992, A033993, A051270, A074969, A176655, A348266.

Sequence in context: A045047 A239344 A195087 * A130897 A336595 A069084

Adjacent sequences: A348879 A348880 A348881 * A348883 A348884 A348885

Keyword

nonn

Author

Metin Sariyar, Nov 02 2021

Extensions

a(13)-a(17) from Amiram Eldar, Nov 02 2021

More terms from David A. Corneth, Nov 02 2021

Status

approved