A376739 Main diagonal of A376738: a(n) is the n-th number which is the product of n (possibly non-distinct) primes having the same number of decimal digits.

2, 6, 18, 40, 108, 224, 480, 1296, 2688, 5760, 12800, 31104, 64512, 138240, 286720, 614400, 1492992, 3096576, 6422528

Offset: 1

Author

Paolo Xausa, Oct 03 2024

Keywords

• nonn
• base
• more

Comments

See A376738 for more information.

First differs from A101695 at n = 10.

Crossrefs

Cf. A101695, A376738.

Programs

Mathematica

A376739[n_] := Module[{m = 2^n - 1}, Do[While[Total[(f = FactorInteger[++m])[[All, 2]]] != n || Length[Union[IntegerLength[f[[All, 1]]]]] > 1], n]; m];
Array[A376739, 15]

Formula

a(n) = A376738(n,n).