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.

A261201 Base-10 representation of A261200.

Original entry on oeis.org

1, 2, 5, 11, 23, 47, 191, 383, 3067, 12269, 196307, 6281839, 50254717, 201018869, 804075479, 1608150959, 102921661397, 1646746582367, 13173972658937, 105391781271503, 210783562543007, 3372537000688127, 26980296005505019, 863369472176160611
Offset: 1

Views

Author

Clark Kimberling, Sep 16 2015

Keywords

Crossrefs

A055011, A261200 and A261201 are all essentially the same sequence.

Programs

  • Mathematica
    b = 2; s = {{1}};
    Do[NestWhile[# + 1 &, 0, ! (PrimeQ[FromDigits[tmp = Join[Last[s], (nn = #;           IntegerDigits[nn - Sum[b^n, {n, l = NestWhile[# + 1 &, 1, ! (nn - (Sum[b^n, {n, #}]) < 0) &] - 1}], b, l + 1])], b]]) &];
    AppendTo[s, tmp], {30}]; Map[FromDigits, s]
    Map[FromDigits, s] (* A261200 *)
    Map[FromDigits[#, b] &, s] (* A261201 *)
    (* Peter J. C. Moses, Aug 06 2015 *)

A055011 a(n+1) = next smallest prime beginning with a(n) when written in binary, starting with 2.

Original entry on oeis.org

2, 5, 11, 23, 47, 191, 383, 3067, 12269, 196307, 6281839, 50254717, 201018869, 804075479, 1608150959, 102921661397, 1646746582367, 13173972658937, 105391781271503, 210783562543007, 3372537000688127, 26980296005505019, 863369472176160611, 6906955777409284889
Offset: 0

Views

Author

Henry Bottomley, May 31 2000

Keywords

Comments

a(5)=191 because a(4)=47 which in binary is 101111, none of 1011110(94) 1011111(95) 10111100(188) 10111101(189) 10111110 (190) are prime, but 10111111(191) is.

Crossrefs

Cf. A048549 for base 10 analog.
A055011, A261200 and A261201 are all essentially the same sequence.

Programs

  • Haskell
    a055011 n = a055011_list !! n
    a055011_list = iterate a208241 2  -- Reinhard Zumkeller, Feb 14 2013
  • Maple
    A055011 := proc(n)
        option remember;
        if n = 0 then
            2 ;
        else
            A208241(procname(n-1)) ;
        end if;
    end proc: # R. J. Mathar, May 06 2017

Formula

a(n+1) = A208241(a(n)). - Reinhard Zumkeller, Feb 14 2013

A261270 Base-10 representation of A261269.

Original entry on oeis.org

3, 7, 29, 59, 239, 479, 3833, 30671, 61343, 981493, 3925973, 62815573, 502524587, 2010098351, 16080786809, 1029170355779, 4116681423119, 65866902769909, 263467611079637, 2107740888637103, 134895416872774619, 17266613359715151259, 1105063255021769680613
Offset: 1

Views

Author

Clark Kimberling, Sep 17 2015

Keywords

Crossrefs

Cf. A261269.

Programs

  • Mathematica
    b = 2; s = {{1}}; Do[NestWhile[# + 1 &, 0, ! (PrimeQ[FromDigits[tmp = Join[Last[s],(nn = #; IntegerDigits[nn - Sum[b^n, {n, l = NestWhile[# + 1 &, 1, ! (nn - (Sum[b^n, {n, #}]) < 0) &] - 1}], b, l + 1])], b]]) &]; AppendTo[s, tmp], {30}]; Map[FromDigits, s]; Map[FromDigits, s] (* A261200 *)
    Map[FromDigits[#, b] &, s] (* A261201 *)
    (* Peter J. C. Moses, Aug 06 2015 *)
Showing 1-3 of 3 results.