A372960 Concatenation of the exponents in the prime factorization of 2*n-1.

0, 1, 1, 1, 2, 1, 1, 11, 1, 1, 11, 1, 2, 3, 1, 1, 11, 11, 1, 11, 1, 1, 21, 1, 2, 11, 1, 11, 11, 1, 1, 21, 11, 1, 11, 1, 1, 12, 11, 1, 4, 1, 11, 11, 1, 11, 11, 11, 1, 21, 1, 1, 111, 1, 1, 11, 1, 11, 21, 11, 2, 11, 3, 1, 11, 1, 11, 31, 1, 1, 11, 11, 11, 12, 1, 1, 21

Offset: 1

Author

Jean-Marc Rebert, Aug 02 2024

Keywords

• nonn
• base

Examples

			a(8) = 11, because 2*8 - 1 = 15 = 3^1 * 5^1 and the concatenation of the exponents of the prime factorization is 11.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A005408, A037916, A375039.

Programs

Mathematica

Join[{0},Table[FromDigits[Flatten[IntegerDigits/@FactorInteger[2n-1][[;;,2]]]],{n,2,80}]] (* Harvey P. Dale, Jun 04 2025 *)

Formula

a(n) = A037916(2*n-1).