A087022 Total number of prime factors of n-th cyclic number.

6, 9, 12, 10, 11, 9, 11, 23, 25, 25, 22, 18, 19, 15, 14, 38, 35, 24, 28, 25, 27, 21, 17, 38, 44, 27, 43, 16, 16, 23, 42, 35, 37, 30, 29, 14, 23, 62, 41, 51, 28, 26, 24, 19, 50, 29, 39, 25, 62, 36, 29

Offset

1,1

Comments

A004042(n) factorized with Dario Alpern's ECM.

Extended using factors of 10^(A001913(n)-1)-1, see Kamada link.

Links

Table of n, a(n) for n=1..51.

Dario A. Alpern, Factorization using the Elliptic Curve Method.

Makoto Kamada, Factorizations of 11...11 (Repunit)

Eric Weisstein's World of Mathematics, Cyclic Number

Formula

a(n) = A001222(A004042(n+1)).

Example

A004042(2) = 142857 = 37*13*11*3^3, therefore a(1) = A087021(1)+2 = 6.

Crossrefs

Cf. A001913, A087020-A087026.

Sequence in context: A125971 A322158 A143710 * A315951 A081392 A225868

Adjacent sequences: A087019 A087020 A087021 * A087023 A087024 A087025

Keyword

nonn,more,hard

Author

Reinhard Zumkeller, Jul 30 2003

Extensions

a(3) corrected, a(12)-a(42) added by Ray Chandler, Nov 16 2011

a(43)-a(51) from Max Alekseyev, May 13 2022

Status

approved