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.

Previous Showing 11-20 of 25 results. Next

A103676 Numbers m such that in binary representation m! contains 5!.

Original entry on oeis.org

5, 10, 12, 22, 23, 25, 27, 29, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 47, 48, 49, 50, 51, 52, 54, 55, 56, 57, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99
Offset: 1

Views

Author

Reinhard Zumkeller, Feb 12 2005

Keywords

Comments

Complement of A103677: A103673(a(n))=1, A103673(A103677(n))=0.

Crossrefs

Programs

  • Mathematica
    Select[Range[100],MemberQ[Partition[IntegerDigits[#!,2],7,1],{1,1,1,1,0,0,0}]&] (* Harvey P. Dale, Apr 09 2012 *)
  • PARI
    is(n)=n=n!; while(n>119, my(e=valuation(n, 2), e1=valuation((n>>=e)+1, 2)); n>>=e1; if(e>2 && e1>3, return(1))); 2 \\ Charles R Greathouse IV, Apr 07 2013

A103677 Numbers m such that in binary representation m! doesn't contain 5!.

Original entry on oeis.org

0, 1, 2, 3, 4, 6, 7, 8, 9, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21, 24, 26, 28, 30, 31, 32, 36, 46, 53, 58, 65
Offset: 1

Views

Author

Reinhard Zumkeller, Feb 12 2005

Keywords

Comments

Conjecture: there are no further terms;
complement of A103676: A103673(a(n))=0, A103673(A103676(n))=1.

Crossrefs

Programs

  • PARI
    is(n)=n=n!; while(n>119, my(e=valuation(n, 2), e1=valuation((n>>=e)+1, 2)); n>>=e1; if(e>2 && e1>3, return(0))); 1 \\ Charles R Greathouse IV, Apr 07 2013

A093684 In binary representation: number of occurrences of n in n!.

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 3, 0, 1, 0, 2, 0, 1, 1, 1, 1, 2, 3, 2, 2, 2, 1, 1, 1, 3, 0, 2, 1, 3, 1, 1, 0, 1, 2, 2, 3, 3, 1, 1, 1, 1, 2, 2, 4, 3, 3, 3, 2, 2, 0, 3, 1, 5, 5, 6, 4, 1, 5, 2, 3, 2, 2, 4, 1, 1, 1, 4, 1, 1, 1, 2, 3, 3, 4, 5, 0, 3, 2, 1, 4, 3, 4, 5, 3, 2, 1, 2, 3, 3, 3, 3, 6, 2, 3, 4, 4, 2
Offset: 1

Views

Author

Reinhard Zumkeller, Apr 10 2004

Keywords

Comments

a(A093685(n)) = 0, a(A093686(n)) > 0.

Examples

			n=12->'1100', 12!=479001600->'11100100011001111110000000000' with three occurrences of '1100': '.1100....1100....1100........', therefore a(12)=3.
		

Crossrefs

Programs

  • Maple
    f:= proc(n) local L,Lf;
      L:= convert(convert(n,binary),string);
      Lf:= convert(convert(n!,binary),string);
      nops([StringTools:-SearchAll(L,Lf)])
    end proc:
    map(f, [$1..100]); # Robert Israel, May 20 2016
  • Mathematica
    non[n_]:=Module[{b=IntegerDigits[n,2],f=IntegerDigits[n!,2]}, Length[ Select[ Partition[ f,Length[b],1],#==b&]]]; Array[non,110] (* Harvey P. Dale, Jun 04 2014 *)

A093710 Numbers k such that in their binary representation all numbers from 1 to k are contained in k!.

Original entry on oeis.org

1, 2, 3, 4, 6, 7, 8, 14, 23, 26, 28, 30, 33, 34, 35, 39, 42, 43, 51, 53, 58, 61, 62, 63, 64, 66, 68, 70, 73, 77, 80, 83, 93, 94, 106, 108, 111, 114, 115, 116, 126, 131, 132, 133, 134, 136, 137, 147, 149, 153, 155, 156, 169, 172, 175, 180, 185, 187, 191, 195, 206
Offset: 1

Views

Author

Reinhard Zumkeller, Apr 11 2004

Keywords

Examples

			6 is in the sequence because 6! = 1011010000_2 which contains 4 = 100_2, 5 = 101_2 and 6 = 110_2 as a substring in the binary expansion. As it contains 4, 5 and 6 in binary it contains the binary expansion of every smaller number than 4 in its binary expansion. - _David A. Corneth_, Aug 05 2025
		

Crossrefs

Complement of A093711.

Formula

A092601(a(n)) = a(n).

A093711 Numbers k such that in their binary representation not all numbers from 1 to k are contained in k!.

Original entry on oeis.org

5, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 27, 29, 31, 32, 36, 37, 38, 40, 41, 44, 45, 46, 47, 48, 49, 50, 52, 54, 55, 56, 57, 59, 60, 65, 67, 69, 71, 72, 74, 75, 76, 78, 79, 81, 82, 84, 85, 86, 87, 88, 89, 90, 91, 92, 95, 96, 97, 98, 99, 100, 101, 102
Offset: 1

Views

Author

Reinhard Zumkeller, Apr 11 2004

Keywords

Crossrefs

Complement of A093710.
A093685 \ {0} is a subsequence.

Formula

A092601(a(n)) < a(n).

A127113 n! in base 6.

Original entry on oeis.org

1, 1, 2, 10, 40, 320, 3200, 35200, 510400, 11440000, 205440000, 3543320000, 115310400000, 2505522400000, 104014341200000, 2440423132000000, 112255444052000000, 3300252314304000000, 143012413513200000000, 5313433311353200000000, 302523154413030400000000
Offset: 0

Views

Author

Artur Jasinski, Jan 05 2007

Keywords

Crossrefs

Programs

  • Mathematica
    FromDigits[IntegerDigits[#,6]]&/@(Range[0,30]!) (* Harvey P. Dale, Jun 18 2019 *)

Formula

a(n) = A007092(A000142(n)). - R. J. Mathar, Jun 09 2020

Extensions

More terms from Harvey P. Dale, Jun 18 2019

A127114 n! in base 7.

Original entry on oeis.org

1, 1, 2, 6, 33, 231, 2046, 20460, 225360, 3040650, 42562410, 663200340, 14604306060, 310211542410, 6204234151200, 163322250505200, 4256423144450400, 134630366022322500, 3634363143602406600, 134462435323300144200, 4233013654405404511500
Offset: 0

Views

Author

Artur Jasinski, Jan 05 2007

Keywords

Comments

Number of digits in A127114(n) = A127033(n) + 1.

Crossrefs

Programs

  • Mathematica
    b = Table[IntegerDigits[n!, 7], {n, 1, 15}]; a = {}; Do[AppendTo[a, FromDigits[b[[x]]]], {x, 1, Length[b]}]; a (*Artur Jasinski*)
    FromDigits[IntegerDigits[#,7]]&/@(Range[0,20]!) (* Harvey P. Dale, Jun 19 2011 *)

Extensions

More terms from Harvey P. Dale, Jun 19 2011

A127115 n! in base 8.

Original entry on oeis.org

1, 1, 2, 6, 30, 170, 1320, 11660, 116600, 1304600, 15657400, 230212400, 3443176000, 56312146000, 1211416624000, 23016735654000, 460356735300000, 12067735663300000, 265756631234600000, 6601271140642200000
Offset: 0

Views

Author

Artur Jasinski, Jan 05 2007

Keywords

Crossrefs

Programs

  • Mathematica
    b = Table[IntegerDigits[n!, 8], {n, 1, 15}]; a = {}; Do[AppendTo[a, FromDigits[b[[x]]]], {x, 1, Length[b]}]; a (*Artur Jasinski*)

A127116 n! in base 9.

Original entry on oeis.org

1, 1, 2, 6, 26, 143, 880, 6820, 61270, 612700, 6740700, 83088500, 1211283600, 17058212600, 270017301300, 4560302022000, 82065335385000, 1648341372414000, 34076827548280000, 725735500635080000, 17178403115182870000
Offset: 0

Views

Author

Artur Jasinski, Jan 05 2007

Keywords

Crossrefs

Programs

  • Mathematica
    b = Table[IntegerDigits[n!, 9], {n, 1, 15}]; a = {}; Do[AppendTo[a, FromDigits[b[[x]]]], {x, 1, Length[b]}]; a (*Artur Jasinski*)

A093686 In binary representation: numbers occurring at least once in their factorial.

Original entry on oeis.org

1, 2, 3, 4, 6, 7, 8, 9, 10, 12, 14, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79
Offset: 1

Views

Author

Reinhard Zumkeller, Apr 10 2004

Keywords

Comments

A093684(a(n)) > 0, complement of A093685.
Almost all numbers are included -- of the first 1000 numbers, only 14 -- i.e., 5, 11, 13, 15, 17, 31, 37, 55, 81, 164, 395, 513, 517, and 619 -- do not appear. In all likelihood, the density of such exceptions gets even smaller as the numbers get larger. - Harvey P. Dale, May 16 2025

Examples

			6!=1*2*3*4*5*6=720 -> '1011010000' where '110'=6 is contained:
'..110.....', therefore 6 is a term.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[80],SequenceCount[IntegerDigits[#!,2],IntegerDigits[#,2]]>0&] (* Harvey P. Dale, May 16 2025 *)
Previous Showing 11-20 of 25 results. Next