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.

A279000 Numbers of the form (11*h+j)*11^k-1 for h,k in N and j in {1,3,4,5,9}.

Original entry on oeis.org

0, 2, 3, 4, 8, 10, 11, 13, 14, 15, 19, 22, 24, 25, 26, 30, 32, 33, 35, 36, 37, 41, 43, 44, 46, 47, 48, 52, 54, 55, 57, 58, 59, 63, 66, 68, 69, 70, 74, 77, 79, 80, 81, 85, 88, 90, 91, 92, 96, 98, 99, 101, 102, 103, 107, 110, 112, 113, 114, 118, 120, 121, 123, 124, 125, 129
Offset: 1

Views

Author

N. J. A. Sloane, Dec 07 2016

Keywords

Comments

Created in a failed attempt to explain sequences J and K on page 10 of Fu and Han (2016). See A279194 and A279195. - N. J. A. Sloane, Dec 15 2016
Numbers n such that the least-significant non-0 digit of n+1 in base 11 is one of {1,3,4,5,9}. - R. J. Mathar, Dec 15 2016
It appears that the correct J and K have form more closely resembling the J and K of F_3(n): n is in J if either k is odd and j is in {2,6,7,8,10} or k is even and j is in {1,3,4,5,9}, and n is in K if either k is even and j is in {2,6,7,8,10} or k is odd and j is in {1,3,4,5,9}. - Charlie Neder, Mar 10 2019

Crossrefs

Complement of A279001.

Programs

  • Maple
    isA279000 := proc(n)
        local x,dgs11,i ;
        x := n+1 ;
        dgs11 := convert(x,base,11) ;
        for i from 1 to nops(dgs11) do
            if op(i,dgs11) in {1,3,4,5,9} then
                return true;
            elif op(i,dgs11) in {2,6,7,8,10} then
                return false;
            end if;
        end do:
        false ;
    end proc:
    for n from 0 to 200 do
        if isA279000(n) then
            printf("%d,",n) ;
        end if;
    end do: # R. J. Mathar, Dec 15 2016
  • Mathematica
    okQ[n_] := MatchQ[IntegerDigits[n+1, 11], {_, 1 | 3 | 4 | 5 | 9, 0...}]; Select[Range[0, 200], okQ] (* Jean-François Alcover, Feb 25 2018, after R. J. Mathar *)
  • Python
    from sympy import integer_log
    def A279000(n):
        def f(x): return n-1+sum(((m:=(x+1)//11**i)-2)//11+(m-6)//11+(m-7)//11+(m-8)//11+(m-10)//11+5 for i in range(integer_log(x+1,11)[0]+1))
        m, k = n-1, f(n-1)
        while m != k: m, k = k, f(k)
        return m # Chai Wah Wu, Feb 23 2025

Extensions

Corrected by Lars Blomberg (10 added, 21 removed, 32 added...), Dec 15 2016

A279194 Numbers of the form {(11*h+p)*11^2k-1 | h,k in N and p in {1,3,4,5,9} } U {(11*h+q)*11^(2k+1)-1 | h,k in N and q in {2,6,7,8,10} }.

Original entry on oeis.org

0, 2, 3, 4, 8, 11, 13, 14, 15, 19, 21, 22, 24, 25, 26, 30, 33, 35, 36, 37, 41, 44, 46, 47, 48, 52, 55, 57, 58, 59, 63, 65, 66, 68, 69, 70, 74, 76, 77, 79, 80, 81, 85, 87, 88, 90, 91, 92, 96, 99, 101, 102, 103, 107, 109, 110, 112, 113, 114, 118, 120, 121, 123, 124, 125, 129
Offset: 1

Views

Author

N. J. A. Sloane, Dec 15 2016

Keywords

Comments

The sequence J related to the Apwenian power series F_{11}(x).

Crossrefs

Programs

  • Mathematica
    isok[n_]:=Module[{ord=IntegerExponent[n+1,11],pq={{1,3,4,5,9},{2,6,7,8,10}}},MemberQ[pq[[Mod[ord,2]+1]],Mod[(n+1)/11^ord,11]]];Select[Range[0,131],isok] (* Ray Chandler, Dec 17 2016 *)

Extensions

Definition (from p. 5, Definition 2.1 of the arXiv reference) provided by Arie Groeneveld, Dec 16 2016
More terms from Ray Chandler, Dec 17 2016

A279195 Numbers of the form {(11*h+p)*11^(2k+1)-1 | h,k in N and p in {1,3,4,5,9} } U {(11*h+q)*11^2k-1 | h,k in N and q in {2,6,7,8,10} }.

Original entry on oeis.org

1, 5, 6, 7, 9, 10, 12, 16, 17, 18, 20, 23, 27, 28, 29, 31, 32, 34, 38, 39, 40, 42, 43, 45, 49, 50, 51, 53, 54, 56, 60, 61, 62, 64, 67, 71, 72, 73, 75, 78, 82, 83, 84, 86, 89, 93, 94, 95, 97, 98, 100, 104, 105, 106, 108, 111, 115, 116, 117, 119, 122, 126, 127, 128, 130, 131
Offset: 1

Views

Author

N. J. A. Sloane, Dec 15 2016

Keywords

Comments

The sequence K related to the Apwenian power series F_{11}(x).

Crossrefs

Programs

  • Mathematica
    isok[n_]:=Module[{ord=IntegerExponent[n+1,11],pq={{2,6,7,8,10},{1,3,4,5,9}}},MemberQ[pq[[Mod[ord,2]+1]],Mod[(n+1)/11^ord,11]]];Select[Range[0,131],isok] (* Ray Chandler, Dec 17 2016 *)

Extensions

Definition (from p. 5, Definition 2.1 of the arXiv reference) provided by Arie Groeneveld, Dec 16 2016
More terms from Ray Chandler, Dec 17 2016
Showing 1-3 of 3 results.