cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A330193 a(n) is the length of the decimal expansion of A330192(n)^A330192(n).

Original entry on oeis.org

1, 1, 1, 2, 3, 4, 5, 6, 8, 9, 11, 55, 77, 88, 444, 555, 666, 888, 999, 1111, 4444, 5555, 6666, 9999, 11111, 55555, 99999, 333333, 444444, 666666, 888888, 999999, 1111111, 7777777, 33333333, 88888888, 333333333, 999999999, 5555555555, 222222222222, 44444444444444
Offset: 1

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Author

Michel Marcus, Dec 05 2019

Keywords

Crossrefs

Cf. A010785 (repdigits), A000312 (n^n), A055642, A066022, A330192.

Programs

  • Mathematica
    Flatten@ Reap[Sow[1]; Do[v = d (10^nd - 1)/9; s = Solve[v-1 <= x Log10[x] < v, x, Integers]; If[s != {}, Sow[v /. s]], {nd, 15}, {d, 9}]][[2, 1]] (* Giovanni Resta, Dec 05 2019 *)

Formula

a(n) = A066022(A330192(n)).
a(n) = A055642(A330192(n)^A330192(n)).

Extensions

a(28)-a(41) from Giovanni Resta, Dec 05 2019
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