A087025 Sum of divisors of n-th cyclic number.

255360, 17205180696931968, 1951532915603927040, 12430490030984319840000, 9956179688423375044684800000, 6080633705911286890368486450696472902951229440, 4809378729404888733987843426081300724182624228548100710400

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, A087024, A087026.

Formula

a(n) = A000203(A004042(n+1)).

Extensions

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