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 1-8 of 8 results.

A250047 Numbers n such that m = floor(n/7) is not coprime to n and, if nonzero, m is also a term of the sequence.

Original entry on oeis.org

2, 3, 4, 5, 6, 14, 16, 18, 20, 21, 24, 27, 28, 30, 32, 34, 35, 40, 42, 44, 45, 46, 48, 98, 100, 102, 104, 112, 114, 116, 118, 126, 128, 129, 130, 132, 140, 142, 144, 145, 146, 147, 150, 153, 168, 170, 171, 172, 174, 189, 192, 195, 196, 198, 200, 202, 210
Offset: 1

Views

Author

Stanislav Sykora, Jan 15 2015

Keywords

Comments

See the comments in A250041 which all apply, except for the setting of the base, b=7. In particular, they define the property RTNC(b).

Links

Crossrefs

Cf. A250041 (b=10), A250046.
Other lists of right-truncatable numbers with the property RTNC(b):
A005823 (b=3), A250037 (b=4), A250039 (b=16), A250043 (b=9), A250045 (b=8), A250049 (b=6), A250051 (b=5).

Programs

  • PARI
    See the link
  • PARI
    is_rtnc(n, b=7) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b; ); return (0); } \\ Michel Marcus, Jan 22 2015

A250037 Numbers n such that m = floor(n/4) is not coprime to n and, if nonzero, m is also a term of the sequence.

Original entry on oeis.org

2, 3, 8, 10, 12, 15, 32, 34, 40, 42, 48, 50, 51, 60, 63, 128, 130, 136, 138, 160, 162, 168, 170, 171, 192, 194, 195, 200, 202, 204, 207, 240, 242, 243, 252, 255, 512, 514, 520, 522, 544, 546, 552, 554, 555, 640, 642, 648, 650, 651, 672, 674, 675, 680, 682
Offset: 1

Views

Author

Stanislav Sykora, Dec 07 2014

Keywords

Comments

See the comments in A250041 which all apply, except for the setting of the base, b=4. In particular, they define the property RTNC(b).
If x =12*k+j, 0 <= j <= 11, then x is in the sequence iff either j is in {0,2,3} and 3*k is in the sequence, or j is in {4,6} and 3*k+1 is in the sequence, or j is in {8,10} and 3*k+2 is in the sequence. - Robert Israel, Dec 22 2014

Links

Crossrefs

Cf. A250036, A250041.
Other lists of right-truncatable numbers with the property RTNC(b):
A005823 (b=3), A250039 (b=16), A250041 (b=10), A250043 (b=9), A250045 (b=8), A250047 (b=7), A250049 (b=6), A250051 (b=5).

Programs

  • Maple
    S:= {}:
for n from 1 to 1000 do
  m:= floor(n/4);
  if igcd(m,n) = 1 then next fi;
  if m > 0 and not member(m,S) then next fi;
  S:= S union {n}
od:
S; # if using Maple 11 or earlier, uncomment the next line
# sort(convert(S,list)); # Robert Israel, Dec 22 2014
  • PARI
    See the link.
  • PARI
    is_rtnc(n, b=4) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b; ); return (0); } \\ Michel Marcus, Jan 22 2015

A250039 Numbers n such that m = floor(n/16) is not coprime to n and, if nonzero, m is also a term of the sequence.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 32, 34, 36, 38, 40, 42, 44, 46, 48, 51, 54, 57, 60, 63, 64, 66, 68, 70, 72, 74, 76, 78, 80, 85, 90, 95, 96, 98, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112, 119, 126, 128, 130, 132, 134, 136, 138, 140, 142
Offset: 1

Views

Author

Stanislav Sykora, Dec 07 2014

Keywords

Comments

See the comments in A250041 which all apply, except for the setting of the base, b=16. In particular, they define the property RTNC(b).
This list is an infinite subset of A248502 with which it shares the first 111 entries.

Links

Crossrefs

Cf. A248502, A250038, A250041.
Other lists of right-truncatable numbers with the property RTNC(b): A005823 (b=3), A250037 (b=4), A250041 (b=10), A250043 (b=9), A250045 (b=8), A250047 (b=7), A250049 (b=6), A250051 (b=5).

Programs

  • PARI
    See the link.
  • PARI
    is_rtnc(n, b=16) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b; ); return (0); } \\ Michel Marcus, Jan 29 2015

A250041 Numbers n such that m = floor(n/10) is not coprime to n and, if nonzero, m is also a term of the sequence.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 8, 9, 20, 22, 24, 26, 28, 30, 33, 36, 39, 40, 42, 44, 46, 48, 50, 55, 60, 62, 63, 64, 66, 68, 69, 70, 77, 80, 82, 84, 86, 88, 90, 93, 96, 99, 200, 202, 204, 205, 206, 208, 220, 222, 224, 226, 228, 240, 242, 243, 244, 246, 248, 249, 260, 262
Offset: 1

Views

Author

Stanislav Sykora, Dec 07 2014

Keywords

Comments

Equivalent definition 1: Assuming a base b (in this case b=10), let us say that a positive integer k has the property RTNC(b) when m=floor(k/b) is not coprime to k, i.e., gcd(k,m)>1. Then k belongs to this sorted list if (i) it has the property RTNC(b) and (ii) m is either 0 or belongs also to the list.
Equivalent definition 2: Every nonempty prefix of a(n) in base b has the property RTNC(b).
Notes: The acronym RTNC stands for 'Right-Truncated is Not Coprime' (negation of the property RTC defined in A250040). We could also say that a(n) are right-truncatable numbers with property RTNC(b).
This particular list is an infinite subset of A248500.

Examples

			243 is a member because (243,24), (24,2) and (2,0) are noncoprime pairs.
155 is not a member because gcd(15,1)=1.

Links

Crossrefs

Cf. A248500, A250040.
Other lists of right-truncatable numbers with the property RTNC(b): A005823 (b=3), A250037 (b=4), A250039 (b=16), A250043 (b=9), A250045 (b=8), A250047 (b=7), A250049 (b=6), A250051 (b=5).

Programs

  • PARI
    See the link.
  • PARI
    is_rtnc(n, b=10) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b; ); return (0); } \\ Michel Marcus, Jan 29 2015

A250042 Numbers n such that m = floor(n/9) is coprime to n and, if nonzero, m is also a term of the sequence.

Original entry on oeis.org

1, 9, 10, 11, 12, 13, 14, 15, 16, 17, 82, 83, 85, 86, 88, 89, 91, 93, 97, 100, 101, 102, 103, 104, 105, 106, 107, 109, 113, 115, 118, 119, 120, 121, 122, 123, 124, 125, 127, 129, 131, 136, 137, 139, 142, 143, 145, 147, 149, 151, 154, 155, 156, 157, 158
Offset: 1

Views

Author

Stanislav Sykora, Jan 15 2015

Keywords

Comments

See the comments in A250040 which all apply, except for the setting of the base, b=9. In particular, they define the property RTC(b).

Links

Crossrefs

Cf. A250040 (b=10), A250043.
Other lists of right-truncatable numbers with the property RTC(b): A250036 (b=4), A250038 (b=16), A250044 (b=8), A250046 (b=7), A250048 (b=6), A250050 (b=5).

Programs

  • PARI
    See the link
  • PARI
    is_rtc(n, b=9) =  {while (((m=gcd(n\b, n)) == 1), if (m == 0, return (1)); if ((n=n\b) == 0, return (1));); return (0);} \\ Michel Marcus, Jan 18 2015

A250045 Numbers n such that m = floor(n/8) is not coprime to n and, if nonzero, m is also a term of the sequence.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 16, 18, 20, 22, 24, 27, 30, 32, 34, 36, 38, 40, 45, 48, 50, 51, 52, 54, 56, 63, 128, 130, 132, 134, 144, 146, 147, 148, 150, 160, 162, 164, 165, 166, 176, 178, 180, 182, 192, 194, 195, 196, 198, 216, 219, 222, 240, 242, 243, 244, 245, 246
Offset: 1

Views

Author

Stanislav Sykora, Jan 15 2015

Keywords

Comments

See the comments in A250041 which all apply, except for the setting of the base, b=8. In particular, they define the property RTNC(b).

Links

Crossrefs

Cf. A250041 (b=10), A250044.
Other lists of right-truncatable numbers with the property RTNC(b):
A005823 (b=3), A250037 (b=4), A250039 (b=16), A250043 (b=9), A250047 (b=7), A250049 (b=6), A250051 (b=5).

Programs

  • PARI
    See the link
  • PARI
    is_rtnc(n, b=8) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b; ); return (0); } \\ Michel Marcus, Jan 22 2015

A250049 Numbers n such that m = floor(n/6) is not coprime to n and, if nonzero, m is also a term of the sequence.

Original entry on oeis.org

2, 3, 4, 5, 12, 14, 16, 18, 21, 24, 26, 28, 30, 35, 72, 74, 75, 76, 84, 86, 88, 96, 98, 100, 108, 110, 111, 112, 126, 129, 144, 146, 147, 148, 156, 158, 160, 168, 170, 172, 180, 182, 183, 184, 185, 210, 215, 432, 434, 435, 436, 444, 446, 448, 450, 453, 455
Offset: 1

Views

Author

Stanislav Sykora, Jan 31 2015

Keywords

Comments

See the comments in A250041 which all apply, except for the setting of the base, b=6. In particular, they define the property RTNC(b).

Links

Crossrefs

Cf. A250041 (b=10), A250046.
Other lists of right-truncatable numbers with the property RTNC(b):
A005823 (b=3), A250037 (b=4), A250039 (b=16), A250043 (b=9), A250045 (b=8), A250047 (b=7), A250051 (b=5).

Programs

  • PARI
    \\ See A250041 for b=6
  • PARI
    is_rtnc(n, b=6) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b;); return (0); } \\ Michel Marcus, Jan 31 2015

A250051 Numbers n such that m = floor(n/5) is not coprime to n and, if nonzero, m is also a term of the sequence.

Original entry on oeis.org

2, 3, 4, 10, 12, 14, 15, 18, 20, 22, 24, 50, 52, 54, 60, 62, 63, 64, 70, 72, 74, 75, 78, 90, 92, 93, 94, 100, 102, 104, 110, 112, 114, 120, 122, 123, 124, 250, 252, 254, 260, 262, 264, 270, 272, 273, 274, 300, 302, 303, 304, 310, 312, 314, 315, 318
Offset: 1

Views

Author

Stanislav Sykora, Jan 31 2015

Keywords

Comments

See the comments in A250041 which all apply, except for the setting of the base, b=5. In particular, they define the property RTNC(b).

Links

Crossrefs

Cf. A250041 (b=10), A250046.
Other lists of right-truncatable numbers with the property RTNC(b):
A005823 (b=3), A250037 (b=4), A250039 (b=16), A250043 (b=9), A250045 (b=8), A250047 (b=7), A250049 (b=6).

Programs

  • PARI
    \\ See A250041 for b=5
  • PARI
    is_rtnc(n, b=5) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b;); return (0);} \\ Michel Marcus, Jan 31 2015
Showing 1-8 of 8 results.

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