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 31-40 of 43 results. Next

A322472 Primes that are not base-9 deletable primes (written in base 10).

Original entry on oeis.org

13, 17, 37, 73, 89, 97, 109, 113, 127, 131, 139, 149, 151, 157, 197, 227, 251, 257, 271, 277, 293, 307, 311, 313, 337, 359, 379, 397, 409, 419, 421, 433, 439, 457, 463, 487, 499, 503, 521, 523, 541, 569, 577, 587, 599, 601, 613, 617, 619, 631, 653, 661, 683, 733, 739, 743, 757, 761
Offset: 1

Views

Author

Robert Price, Dec 09 2018

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.
Complement of all primes and A322471.

Crossrefs

Programs

  • Mathematica
    b = 9; d = {};
    p = Select[Range[2, 10000], PrimeQ[#] &];
    For[i = 1, i <= Length[p], i++,
    c = IntegerDigits[p[[i]], b];
    If[Length[c] == 1, AppendTo[d, p[[i]]]; Continue[]];
    For[j = 1, j <= Length[c], j++,
    t = Delete[c, j];
    If[t[[1]] == 0, Continue[]];
    If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; Break[]]]]; Complement[Table[Prime[n], {n, PrimePi[Last[d]]}], d] (* Robert Price, Dec 09 2018 *)

A322476 Primes that are not base-11 deletable primes (written in base 10).

Original entry on oeis.org

11, 17, 19, 53, 67, 89, 97, 103, 107, 109, 127, 131, 137, 139, 157, 163, 173, 179, 181, 191, 193, 197, 199, 223, 227, 229, 239, 241, 269, 277, 281, 307, 311, 379, 383, 397, 401, 419, 421, 431, 443, 449, 463, 467, 491, 499, 503, 541, 547, 569, 571, 577, 587, 593, 599, 601, 607, 613
Offset: 1

Views

Author

Robert Price, Dec 09 2018

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.
Complement of all primes and A322475.

Crossrefs

Programs

  • Mathematica
    b = 11; d = {};
    p = Select[Range[2, 10000], PrimeQ[#] &];
    For[i = 1, i <= Length[p], i++,
    c = IntegerDigits[p[[i]], b];
    If[Length[c] == 1, AppendTo[d, p[[i]]]; Continue[]];
    For[j = 1, j <= Length[c], j++,
    t = Delete[c, j];
    If[t[[1]] == 0, Continue[]];
    If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; Break[]]]]; Complement[Table[Prime[n], {n, PrimePi[Last[d]]}], d] (* Robert Price, Dec 09 2018 *)

A322478 Primes that are not base-12 deletable primes (written in base 10).

Original entry on oeis.org

13, 73, 97, 109, 157, 193, 241, 313, 337, 397, 409, 421, 431, 577, 601, 631, 661, 673, 691, 797, 877, 929, 937, 941, 1009, 1019, 1021, 1033, 1063, 1093, 1103, 1117, 1123, 1129, 1151, 1153, 1201, 1249, 1297, 1303, 1307, 1321, 1381, 1429, 1439, 1453, 1489, 1549, 1597, 1609, 1619, 1657, 1693, 1741
Offset: 1

Views

Author

Robert Price, Dec 09 2018

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.
Complement of all primes and A322477.

Crossrefs

Programs

  • Mathematica
    b = 12; d = {};
    p = Select[Range[2, 10000], PrimeQ[#] &];
    For[i = 1, i <= Length[p], i++,
    c = IntegerDigits[p[[i]], b];
    If[Length[c] == 1, AppendTo[d, p[[i]]]; Continue[]];
    For[j = 1, j <= Length[c], j++,
    t = Delete[c, j];
    If[t[[1]] == 0, Continue[]];
    If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; Break[]]]]; Complement[Table[Prime[n], {n, PrimePi[Last[d]]}], d] (* Robert Price, Dec 09 2018 *)

A096237 Number of n-digit base-4 deletable primes.

Original entry on oeis.org

2, 3, 9, 26, 75, 213, 615, 1853, 5854, 18664, 61248, 205300, 698575, 2409598, 8408050, 29657194
Offset: 1

Views

Author

Michael Kleber, Feb 28 2003

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime. "Digit" means digit in base b.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Crossrefs

Programs

  • Mathematica
    b = 4; a = {2}; d = {2, 3};
    For[n = 2, n <= 8, n++,
      p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
      ct = 0;
      For[i = 1, i <= Length[p], i++,
       c = IntegerDigits[p[[i]], b];
       For[j = 1, j <= n, j++,
        t = Delete[c, j];
        If[t[[1]] == 0, Continue[]];
        If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; ct++;
         Break[]]]];
      AppendTo[a, ct]];
    a (* Robert Price, Nov 12 2018 *)
  • Python
    from sympy import isprime
    from sympy.ntheory.digits import digits
    def ok(n, prevset, base=4):
        if not isprime(n): return False
        s = "".join(str(d) for d in digits(n, base)[1:])
        si = (s[:i]+s[i+1:] for i in range(len(s)))
        return any(t[0] != '0' and int(t, base) in prevset for t in si)
    def afind(terms):
        alst = [2]
        s, snxt, base = {2, 3}, set(), 4
        print(len(s), end=", ")
        for n in range(2, terms+1):
            for i in range(base**(n-1), base**n):
                if ok(i, s):
                    snxt.add(i)
            s, snxt = snxt, set()
            print(len(s), end=", ")
    afind(10) # Michael S. Branicky, Jan 17 2022

Extensions

a(6)-a(15) from Ryan Propper, Jul 19 2005
a(16) from Michael S. Branicky, Jan 17 2022

A096238 Number of n-digit base-5 deletable primes.

Original entry on oeis.org

2, 6, 14, 32, 69, 156, 377, 855, 2072, 5131, 12922, 32619, 83945, 217305, 571560, 1517012, 4056107
Offset: 1

Views

Author

Michael Kleber, Feb 28 2003

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime. "Digit" means digit in base b.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Crossrefs

Programs

  • Mathematica
    b = 5; a = {2}; d = {2, 3};
    For[n = 2, n <= 8, n++,
      p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
      ct = 0;
      For[i = 1, i <= Length[p], i++,
       c = IntegerDigits[p[[i]], b];
       For[j = 1, j <= n, j++,
        t = Delete[c, j];
        If[t[[1]] == 0, Continue[]];
        If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; ct++;
         Break[]]]];
      AppendTo[a, ct]];
    a (* Robert Price, Nov 12 2018 *)

Extensions

12 more terms from Ryan Propper, Jul 19 2005

A096239 Number of n-digit base-6 deletable primes.

Original entry on oeis.org

3, 7, 32, 135, 597, 2787, 13374, 66071, 335895, 1743974, 9216391, 49420750, 268312356
Offset: 1

Views

Author

Michael Kleber, Feb 28 2003

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime. "Digit" means digit in base b.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Crossrefs

Programs

  • Mathematica
    b = 6; a = {3}; d = {2, 3, 5};
    For[n = 2, n <= 5, n++,
      p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
      ct = 0;
      For[i = 1, i <= Length[p], i++,
       c = IntegerDigits[p[[i]], b];
       For[j = 1, j <= n, j++,
        t = Delete[c, j];
        If[t[[1]] == 0, Continue[]];
        If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; ct++;
         Break[]]]];
      AppendTo[a, ct]];
    a (* Robert Price, Nov 12 2018 *)
  • Python
    from sympy import isprime
    from sympy.ntheory.digits import digits
    def ok(n, prevset, base=6):
        if not isprime(n): return False
        s = "".join(str(d) for d in digits(n, base)[1:])
        si = (s[:i]+s[i+1:] for i in range(len(s)))
        return any(t[0] != '0' and int(t, base) in prevset for t in si)
    def afind(terms):
        alst = [3]
        s, snxt, base = {2, 3, 5}, set(), 6
        print(len(s), end=", ")
        for n in range(2, terms+1):
            for i in range(base**(n-1), base**n):
                if ok(i, s):
                    snxt.add(i)
            s, snxt = snxt, set()
            print(len(s), end=", ")
    afind(8) # Michael S. Branicky, Jan 17 2022

Extensions

a(6)-a(11) from Ryan Propper, Jul 19 2005
a(12)-a(13) from Michael S. Branicky, Jan 17 2022

A096240 Number of n-digit base-7 deletable primes.

Original entry on oeis.org

3, 7, 21, 59, 184, 534, 1620, 4889, 15607, 50138, 165569, 551580, 1860565, 6345080
Offset: 1

Views

Author

Michael Kleber, Feb 28 2003

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime. "Digit" means digit in base b.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Crossrefs

Programs

  • Mathematica
    b = 7; a = {3}; d = {2, 3, 5};
    For[n = 2, n <= 7, n++,
      p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
      ct = 0;
      For[i = 1, i <= Length[p], i++,
       c = IntegerDigits[p[[i]], b];
       For[j = 1, j <= n, j++,
        t = Delete[c, j];
        If[t[[1]] == 0, Continue[]];
        If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; ct++;
         Break[]]]];
      AppendTo[a, ct]];
    a (* Robert Price, Nov 12 2018 *)

Extensions

9 more terms from Ryan Propper, Jul 19 2005

A096241 Number of n-digit base-8 deletable primes.

Original entry on oeis.org

4, 14, 50, 238, 1123, 5792, 30598, 166056, 927639, 5308458, 30984757
Offset: 1

Views

Author

Michael Kleber, Feb 28 2003

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime. "Digit" means digit in base b.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Crossrefs

Programs

  • Mathematica
    b = 8; a = {4}; d = {2, 3, 5, 7};
    For[n = 2, n <= 5, n++,
      p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
      ct = 0;
      For[i = 1, i <= Length[p], i++,
       c = IntegerDigits[p[[i]], b];
       For[j = 1, j <= n, j++,
        t = Delete[c, j];
        If[t[[1]] == 0, Continue[]];
        If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; ct++;
         Break[]]]];
      AppendTo[a, ct]];
    a (* Robert Price, Nov 13 2018 *)
  • Python
    from sympy import isprime
    def ok(n, prevset, base=8):
        if not isprime(n): return False
        s = oct(n)[2:]
        si = (s[:i]+s[i+1:] for i in range(len(s)))
        return any(t[0] != '0' and int(t, base) in prevset for t in si)
    def afind(terms):
        s, snxt = {2, 3, 5, 7}, set()
        print(len(s), end=", ")
        for n in range(2, terms+1):
            for i in range(8**(n-1), 8**n):
                if ok(i, s):
                    snxt.add(i)
            s, snxt = snxt, set()
            print(len(s), end=", ")
    afind(7) # Michael S. Branicky, Jan 14 2022

Extensions

a(6)-a(10) from Ryan Propper, Jul 19 2005
a(11) from D. S. McNeil, Dec 08 2009

A096242 Number of n-digit base-9 deletable primes.

Original entry on oeis.org

4, 14, 58, 221, 911, 3638, 14687, 61435, 262189, 1140171
Offset: 1

Views

Author

Michael Kleber, Feb 28 2003

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime. "Digit" means digit in base b.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Crossrefs

Programs

  • Mathematica
    b = 9; a = {4}; d = {2, 3, 5, 7};
    For[n = 2, n <= 5, n++,
      p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
      ct = 0;
      For[i = 1, i <= Length[p], i++,
       c = IntegerDigits[p[[i]], b];
       For[j = 1, j <= n, j++,
        t = Delete[c, j];
        If[t[[1]] == 0, Continue[]];
        If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; ct++;
         Break[]]]];
      AppendTo[a, ct]];
    a (* Robert Price, Nov 13 2018 *)

Extensions

5 more terms from Ryan Propper, Jul 19 2005

A096244 Number of n-digit base-11 deletable primes.

Original entry on oeis.org

4, 16, 73, 288, 1117, 4472, 18120, 74643, 315174, 1348936
Offset: 1

Views

Author

Michael Kleber, Feb 28 2003

Keywords

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime. "Digit" means digit in base b.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Crossrefs

Programs

  • Mathematica
    b = 11; a = {4}; d = {2, 3, 5, 7};
    For[n = 2, n <= 5, n++,
      p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
      ct = 0;
      For[i = 1, i <= Length[p], i++,
       c = IntegerDigits[p[[i]], b];
       For[j = 1, j <= n, j++,
        t = Delete[c, j];
        If[t[[1]] == 0, Continue[]];
        If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; ct++;
         Break[]]]];
      AppendTo[a, ct]];
    a (* Robert Price, Nov 13 2018 *)

Extensions

5 more terms from Ryan Propper, Jul 19 2005
Previous Showing 31-40 of 43 results. Next