A122262 Number of numbers having only factors that are Pierpont primes.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 20, 20, 21, 22, 23, 24, 25, 25, 26, 26, 27, 27, 28, 29, 30, 31, 32, 33, 34, 34, 35, 35, 35, 36, 36, 36, 37, 38, 39, 40, 41, 41, 42, 42, 43, 44, 44, 44, 45, 45, 45, 46, 47, 48, 48, 48, 49, 49, 50, 50, 51

Offset: 1

Author

Reinhard Zumkeller, Aug 29 2006

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, Pierpont Prime.

Crossrefs

Partial sums of A122261.

Cf. A005109.

Programs

Mathematica

smooth3Q[n_] := Times @@ ({2, 3}^IntegerExponent[n, {2, 3}]) == n; s[n_] := Boole@ AllTrue[FactorInteger[n][[;;, 1]]-1, smooth3Q]; s[1] = 1; Accumulate[Table[s[n], {n, 1, 100}]] (* Amiram Eldar, May 14 2025 *)