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.

Showing 1-3 of 3 results.

A263112 a(n) = F(F(n)) mod n, where F = Fibonacci = A000045.

Original entry on oeis.org

0, 1, 1, 2, 0, 3, 2, 2, 1, 5, 1, 0, 8, 13, 10, 2, 12, 15, 5, 10, 1, 1, 1, 0, 0, 25, 1, 2, 5, 15, 27, 2, 10, 33, 20, 0, 1, 1, 34, 10, 40, 21, 18, 2, 10, 1, 1, 0, 1, 25, 1, 2, 16, 21, 5, 26, 37, 1, 7, 0, 33, 27, 1, 2, 40, 21, 5, 2, 1, 15, 1, 0, 46, 1, 25, 2, 68
Offset: 1

Views

Author

Alois P. Heinz, Oct 09 2015

Keywords

Crossrefs

Programs

  • Maple
    F:= n-> (<<0|1>, <1|1>>^n)[1, 2]:
    p:= (M, n, k)-> map(x-> x mod k, `if`(n=0, <<1|0>, <0|1>>,
              `if`(n::even, p(M, n/2, k)^2, p(M, n-1, k).M))):
    a:= n-> p(<<0|1>, <1|1>>, F(n), n)[1, 2]:
    seq(a(n), n=1..80);
  • Mathematica
    F[n_] := MatrixPower[{{0, 1}, {1, 1}}, n][[1, 2]];
    p[M_, n_, k_] := Mod[#, k]& /@ If[n == 0, {{1, 0}, {0, 1}}, If[EvenQ[n], MatrixPower[p[M, n/2, k], 2], p[M, n - 1, k].M]];
    a[n_] := p[{{0, 1}, {1, 1}}, F[n], n][[1, 2]];
    Table[a[n], {n, 1, 80}] (* Jean-François Alcover, Oct 29 2024, after Alois P. Heinz *)

Formula

a(n) = A007570(n) mod n.

A338889 a(n) = L(L(L(n))) mod L(L(n)), where L = Lucas numbers = A000032.

Original entry on oeis.org

1, 0, 3, 1, 1, 1, 0, 1, 1, 29, 7, 1, 19679776435706023589554718882448088434898811874077010905231927243854, 1, 7
Offset: 0

Views

Author

Alois P. Heinz, Nov 14 2020

Keywords

Comments

a(21) = 2992285359..7163788371 has 5090 decimal digits.

Crossrefs

Programs

  • Maple
    b:= proc(n) local r, M, p; r, M, p:=
          <<1|0>, <0|1>>, <<0|1>, <1|1>>, n;
          do if irem(p, 2, 'p')=1 then r:=
            `if`(nargs=1, r.M, r.M mod args[2]) fi;
             if p=0 then break fi; M:=
            `if`(nargs=1, M.M, M.M mod args[2])
          od; (r.<<2, 1>>)[1$2]
        end:
    a:= n-> (h-> b(h$2) mod h)(b(b(n))):
    seq(a(n), n=0..15);

Formula

a(n) = A262361(n) mod A005371(n).

A338638 a(n) = L(L(n)) mod L(n), where L = Lucas numbers = A000032.

Original entry on oeis.org

1, 0, 1, 3, 1, 1, 0, 1, 1, 7, 4, 1, 199, 1, 4, 843, 1, 1, 0, 1, 29, 123, 4, 1, 3, 199, 4, 39603, 29, 1, 5778, 1, 1, 7, 4, 17622890, 12752043, 1, 4, 39603, 7881196, 1, 5778, 1, 29, 7, 4, 1, 3, 1149851, 28143689044, 7, 29, 1, 0, 312119004790, 6643838879, 7, 4, 1
Offset: 0

Views

Author

Alois P. Heinz, Nov 04 2020

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) local r, M, p; r, M, p:=
          <<1|0>, <0|1>>, <<0|1>, <1|1>>, n;
          do if irem(p, 2, 'p')=1 then r:=
            `if`(nargs=1, r.M, r.M mod args[2]) fi;
             if p=0 then break fi; M:=
            `if`(nargs=1, M.M, M.M mod args[2])
          od; (r.<<2, 1>>)[1$2]
        end:
    a:= n-> (f-> b(f$2) mod f)(b(n)):
    seq(a(n), n=0..60);
  • Mathematica
    Table[Mod[LucasL[LucasL[n]],LucasL[n]],{n,0,60}] (* Harvey P. Dale, Jul 04 2022 *)

Formula

a(n) = A005371(n) mod A000032(n).
a(n) = 0 for n in { A016089 }.
Showing 1-3 of 3 results.