A087024 Number of divisors of n-th cyclic number.

32, 384, 1280, 576, 1536, 384, 1536, 4194304, 16777216, 3538944, 1769472, 110592, 221184, 13824, 6912, 48318382080, 9663676416, 3538944, 75497472, 14155776, 56623104, 884736, 55296, 57982058496, 3710851743744, 37748736, 695784701952, 27648, 27648, 2654208

Offset: 1

Author

Reinhard Zumkeller, Jul 30 2003

Keywords

• nonn

Comments

Calculated with Dario Alpern's ECM.

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

Links

• Max Alekseyev, Table of n, a(n) for n = 1..51 (first 42 terms from Ray Chandler)
• Dario A. Alpern, Factorization using the Elliptic Curve Method.
• Makoto Kamada, Factorizations of 11...11 (Repunit)
• Eric Weisstein's World of Mathematics, Cyclic Number
• Eric Weisstein's World of Mathematics, Divisor Function

Crossrefs

Cf. A001913, A087020, A087021, A087022, A087023, A087025, A087026.

Formula

a(n) = A000005(A004042(n+1)).

Extensions

a(12)-a(42) from Ray Chandler, Nov 16 2011