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 1-6 of 6 results.

A256290 Numbers which have only digits 4 and 5 in base 10.

Original entry on oeis.org

4, 5, 44, 45, 54, 55, 444, 445, 454, 455, 544, 545, 554, 555, 4444, 4445, 4454, 4455, 4544, 4545, 4554, 4555, 5444, 5445, 5454, 5455, 5544, 5545, 5554, 5555, 44444, 44445, 44454, 44455, 44544, 44545, 44554, 44555, 45444, 45445, 45454, 45455, 45544
Offset: 1

Views

Author

M. F. Hasler, Mar 27 2015

Keywords

Crossrefs

Cf. A007088 (digits 0 & 1), A007931 (digits 1 & 2), A032810 (digits 2 & 3), A032834 (digits 3 & 4), A256291 (digits 5 & 6), A256292 (digits 6 & 7), A256340 (digits 7 & 8), A256341 (digits 8 & 9).

Programs

  • Magma
    [n: n in [1..60000] | Set(IntegerToSequence(n, 10)) subset {5, 4}];
    
  • Magma
    [n: n in [1..100000] | Set(Intseq(n)) subset {4,5}]; // Vincenzo Librandi, Aug 19 2016
    
  • Mathematica
    Flatten[Table[FromDigits[#,10]&/@Tuples[{4,5},n],{n,5}]]
  • PARI
    A256290(n)=vector(#n=binary(n+1)[2..-1],i,10^(#n-i))*n~+10^#n\9*4
    
  • Python
    def A256290(n): return int(bin(n+1)[3:])+(10**((n+1).bit_length()-1)-1<<2)//9 # Chai Wah Wu, Jul 15 2023

Formula

a(n) = A007931(n) + A002277(A000523(n+1)) = A032834(n) + A256077(n) etc.

A256291 Numbers which have only digits 5 and 6 in base 10.

Original entry on oeis.org

5, 6, 55, 56, 65, 66, 555, 556, 565, 566, 655, 656, 665, 666, 5555, 5556, 5565, 5566, 5655, 5656, 5665, 5666, 6555, 6556, 6565, 6566, 6655, 6656, 6665, 6666, 55555, 55556, 55565, 55566, 55655, 55656, 55665, 55666, 56555, 56556
Offset: 1

Views

Author

M. F. Hasler, Mar 27 2015

Keywords

Crossrefs

Cf. A007088 (digits 0 & 1), A007931 (digits 1 & 2), A032810 (digits 2 & 3), A032834 (digits 3 & 4), A256290 (digits 4 & 5), A256292 (digits 6 & 7), A256340 (digits 7 & 8), A256341 (digits 8 & 9).

Programs

  • Magma
    [n: n in [1..60000] | Set(IntegerToSequence(n, 10)) subset {5, 6}];
    
  • Magma
    [n: n in [1..100000] | Set(Intseq(n)) subset {5,6}]; // :Vincenzo Librandi_, Aug 19 2016
  • Mathematica
    Flatten[Table[FromDigits[#,10]&/@Tuples[{5,6},n],{n,5}]]
  • PARI
    A256291(n)=vector(#n=binary(n+1)[2..-1],i,10^(#n-i))*n~+10^#n\9*5
    

Formula

a(n) = A007931(n) + A002278(A000523(n+1)) = A256290(n) + A256077(n) etc.

A032834 Numbers with digits 3 and 4 only.

Original entry on oeis.org

3, 4, 33, 34, 43, 44, 333, 334, 343, 344, 433, 434, 443, 444, 3333, 3334, 3343, 3344, 3433, 3434, 3443, 3444, 4333, 4334, 4343, 4344, 4433, 4434, 4443, 4444, 33333, 33334, 33343, 33344, 33433, 33434, 33443, 33444, 34333, 34334
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A032829-A032833 (in other bases), A102659 (Lyndon words in this sequence), A007088 (digits 0 & 1), A007931 (digits 1 & 2), A032810 (digits 2 & 3), A256290 (digits 4 & 5), A256291 (digits 5 & 6), A256292 (digits 6 & 7), A256340 (digits 7 & 8), A256341 (digits 8 & 9).

Programs

  • Magma
    [n: n in [1..35000] | Set(IntegerToSequence(n, 10)) subset {3, 4}]; // Vincenzo Librandi, May 30 2012
    
  • Maple
    S[1]:= [3,4]:
    for d from 2 to 5 do S[d]:= map(t -> (10*t+3,10*t+4), S[d-1]) od:
    seq(op(S[d]),d=1..5); # Robert Israel, Apr 03 2017
  • Mathematica
    Flatten[Table[FromDigits[#,10]&/@Tuples[{3,4},n],{n,5}]] (* Vincenzo Librandi, May 30 2012 *)
  • PARI
    A032834(n)=vector(#n=binary(n+1)[2..-1],i,10^(#n-i))*n~+10^#n\3 \\ M. F. Hasler, Mar 27 2015

Formula

a(n) = A007931(n) + A002276(A000523(n+1)) = A032810(n) + A256077(n) etc. - M. F. Hasler, Mar 27 2015
From Robert Israel, Apr 03 2017: (Start)
a(2*n+1) = 10*a(n)+3.
a(2*n+2) = 10*a(n)+4.
G.f. g(x) satisfies g(x) = 10*(x+x^2)*g(x^2) + x*(3+4*x)/(1-x^2). (End)

Extensions

Crossrefs added by M. F. Hasler, Mar 27 2015
Name corrected by Robert Israel, Apr 03 2017

A256292 Numbers which have only digits 6 and 7 in base 10.

Original entry on oeis.org

6, 7, 66, 67, 76, 77, 666, 667, 676, 677, 766, 767, 776, 777, 6666, 6667, 6676, 6677, 6766, 6767, 6776, 6777, 7666, 7667, 7676, 7677, 7766, 7767, 7776, 7777, 66666, 66667, 66676, 66677, 66766, 66767, 66776, 66777, 67666, 67667
Offset: 1

Views

Author

M. F. Hasler, Mar 27 2015

Keywords

Crossrefs

Cf. A007088 (digits 0 & 1), A007931 (digits 1 & 2), A032810 (digits 2 & 3), A032834 (digits 3 & 4), A256290 (digits 4 & 5), A256291 (digits 5 & 6), A256340 (digits 7 & 8), A256341 (digits 8 & 9).

Programs

  • Magma
    [n: n in [1..35000] | Set(IntegerToSequence(n, 10)) subset {7, 6}];
    
  • Magma
    [n: n in [1..100000] | Set(Intseq(n)) subset {6,7}]; // Vincenzo Librandi, Aug 19 2016
  • Mathematica
    Flatten[Table[FromDigits[#,10]&/@Tuples[{6,7},n],{n,5}]]
  • PARI
    A256292(n)=vector(#n=binary(n+1)[2..-1],i,10^(#n-i))*n~+10^#n\9*6
    

Formula

a(n) = A007931(n) + A002279(A000523(n+1)) = A256291(n) + A256077(n) etc.

A256340 Numbers which have only digits 7 and 8 in base 10.

Original entry on oeis.org

7, 8, 77, 78, 87, 88, 777, 778, 787, 788, 877, 878, 887, 888, 7777, 7778, 7787, 7788, 7877, 7878, 7887, 7888, 8777, 8778, 8787, 8788, 8877, 8878, 8887, 8888, 77777, 77778, 77787, 77788, 77877, 77878, 77887, 77888, 78777, 78778, 78787, 78788, 78877, 78878
Offset: 1

Views

Author

M. F. Hasler, Mar 27 2015

Keywords

Crossrefs

Cf. A007088 (digits 0 & 1), A007931 (digits 1 & 2), A032810 (digits 2 & 3), A032834 (digits 3 & 4), A256290 (digits 4 & 5), A256291 (digits 5 & 6), A256292 (digits 6 & 7), A256341 (digits 8 & 9).

Programs

  • Magma
    [n: n in [1..35000] | Set(IntegerToSequence(n, 10)) subset {7, 8}];
    
  • Magma
    [n: n in [1..100000] | Set(Intseq(n)) subset {7,8}]; // Vincenzo Librandi, Aug 19 2016
    
  • Mathematica
    Flatten[Table[FromDigits[#,10]&/@Tuples[{7,8},n],{n,5}]]
  • PARI
    A256340(n)=vector(#n=binary(n+1)[2..-1],i,10^(#n-i))*n~+10^#n\9*7
    
  • Python
    def a(n): return int(bin(n+1)[3:].replace('0', '7').replace('1', '8'))
    print([a(n) for n in range(1, 45)]) # Michael S. Branicky, Jul 08 2021

Formula

a(n) = A007931(n) + A002280(A000523(n+1)) = A256292(n) + A256077(n) etc.

A256341 Numbers which have only digits 8 and 9 in base 10.

Original entry on oeis.org

8, 9, 88, 89, 98, 99, 888, 889, 898, 899, 988, 989, 998, 999, 8888, 8889, 8898, 8899, 8988, 8989, 8998, 8999, 9888, 9889, 9898, 9899, 9988, 9989, 9998, 9999, 88888, 88889, 88898, 88899, 88988, 88989, 88998, 88999, 89888, 89889
Offset: 1

Views

Author

M. F. Hasler, Mar 27 2015

Keywords

Crossrefs

Cf. A007088 (digits 0 & 1), A007931 (digits 1 & 2), A032810 (digits 2 & 3), A032834 (digits 3 & 4), A256290 (digits 4 & 5) - A256292 (digits 6 & 7), A256340 (digits 7 & 8).

Programs

  • Magma
    [n: n in [1..35000] | Set(IntegerToSequence(n, 10)) subset {8, 9}];
    
  • Magma
    [n: n in [1..100000] | Set(Intseq(n)) subset {8,9}]; // Vincenzo Librandi, Aug 19 2016
    
  • Mathematica
    Flatten[Table[FromDigits[#,10]&/@Tuples[{8,9},n],{n,5}]]
  • PARI
    A256341(n)=vector(#n=binary(n+1)[2..-1],i,10^(#n-i))*n~+10^#n\9*8
    
  • Python
    def a(n): return int(bin(n+1)[3:].replace('0', '8').replace('1', '9'))
    print([a(n) for n in range(1, 45)]) # Michael S. Branicky, Aug 09 2021

Formula

a(n) = A007931(n) + A002281(A000523(n+1)) = A256341(n) + A256077(n) etc.
Showing 1-6 of 6 results.