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.

A227817 Decimal expansion of limit of H(c(n)) - H(c(n-1)), where c = A227816 and H = harmonic number.

Original entry on oeis.org

9, 1, 0, 5, 2, 3, 2, 6, 2, 5, 0, 8, 5, 4, 9, 4, 0, 2, 9, 9, 7, 6, 6, 1, 7, 2, 4, 6, 7, 9, 9, 9, 7, 1, 8, 1, 3, 4, 7, 1, 5, 2, 4, 3, 8, 2, 9, 7, 0, 9
Offset: 0

Views

Author

Clark Kimberling, Jul 31 2013

Keywords

Examples

			0.91052326250854940299766172467999718134715243829709...
		

Crossrefs

Cf. A001008, A002805 (numerator and denominator of harmonic numbers).

Programs

  • Mathematica
    z = 300; h[n_] := h[n] = HarmonicNumber[N[n, 500]]; x = 3; y = 6; a[1] = -1 + Ceiling[w /. FindRoot[h[w] == 2 h[y] - h[x - 1], {w, 1}, WorkingPrecision -> 400]]; a[2] = -1 + Ceiling[w /. FindRoot[h[w] == 2 h[a[1]] - h[y], {w, a[1]}, WorkingPrecision -> 400]]; Do[s = 0; a[t] = -1 + Ceiling[w /. FindRoot[h[w] == 2 h[a[t - 1]] - h[a[t - 2]], {w, a[t - 1]}, WorkingPrecision -> 400]], {t, 3, z}]; m = Map[a, Range[z]]; (* A227816 *)
    x1 = N[Table[h[a[t]] - h[a[t - 1]], {t, 2, z, 50}], 50]
    Last[RealDigits[x1, 10]]  (* A227817 *)
    x2 = N[Table[a[n]/a[n - 1], {n, 2, z, 50}], 50]  (* A227818 *)
    Last[RealDigits[x2, 10]]   (* A227818 *)
    (* Peter J. C. Moses, Jul 23 2013 *)