A096246 -id:A096246 - cp's OEIS frontend

A321910 Base-7 deletable primes (written in base 10).

2, 3, 5, 17, 19, 23, 31, 37, 41, 47, 101, 103, 131, 137, 139, 149, 163, 167, 191, 199, 223, 227, 233, 241, 251, 263, 293, 311, 313, 317, 331, 691, 709, 719, 727, 733, 787, 823, 853, 877, 887, 919, 929, 937, 977, 983, 997, 1013, 1019, 1021, 1031, 1049, 1129, 1171, 1367, 1399, 1409, 1511

Offset: 1

Robert Price, Nov 29 2018

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.

Robert Price, Table of n, a(n) for n = 1..808

Cf. A080608, A080603, A096235-A096246.

b = 7; 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[]]]];
d (* Robert Price, Dec 06 2018 *)

A322173 Base-6 deletable primes (written in base 10).

Original entry on oeis.org

2, 3, 5, 11, 13, 17, 19, 23, 29, 31, 41, 47, 53, 59, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 227, 233, 239, 251, 257, 263, 269, 281, 283, 293, 311, 313, 317, 347, 353, 359, 373, 379, 383, 389, 397

Offset: 1

Robert Price, Nov 29 2018

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.

Robert Price, Table of n, a(n) for n = 1..3561

Cf. A080608, A080603, A096235-A096246.

b = 6; 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[]]]];
d (* Robert Price, Dec 06 2018 *)

A322471 Base-9 deletable primes (written in base 10).

Original entry on oeis.org

2, 3, 5, 7, 11, 19, 23, 29, 31, 41, 43, 47, 53, 59, 61, 67, 71, 79, 83, 101, 103, 107, 137, 163, 167, 173, 179, 181, 191, 193, 199, 211, 223, 229, 233, 239, 241, 263, 269, 281, 283, 317, 331, 347, 349, 353, 367, 373, 383, 389, 401, 431, 443, 449, 461, 467, 479, 491, 509, 547, 557, 563

Offset: 1

Robert Price, Dec 09 2018

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.

Robert Price, Table of n, a(n) for n = 1..327

Cf. A080608, A080603, A096235-A096246.

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[]]]];
d (* Robert Price, Dec 09 2018 *)

A322474 Primes that are not base-10 deletable primes (written in base 10).

Original entry on oeis.org

11, 19, 41, 61, 89, 101, 109, 149, 151, 181, 191, 199, 211, 227, 241, 251, 257, 277, 281, 349, 389, 401, 409, 419, 421, 449, 461, 491, 499, 521, 541, 557, 577, 587, 601, 619, 641, 661, 691, 727, 757, 787, 809, 811, 821, 827, 857, 877, 881, 887, 911, 919, 941, 991, 1009, 1019, 1021, 1049, 1051, 1061

Offset: 1

Robert Price, Dec 09 2018

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. Thus 2003 is in this sequence but not in A081027.
Complement of all nonprimes and A305352.

Robert Price, Table of n, a(n) for n = 1..530

Cf. A080608, A080603, A096235-A096246, A321657, A305352, A081027.

b = 10; 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 *)

A322475 Base-11 deletable primes (written in base 10).

Original entry on oeis.org

2, 3, 5, 7, 13, 23, 29, 31, 37, 41, 43, 47, 59, 61, 71, 73, 79, 83, 101, 113, 149, 151, 167, 211, 233, 251, 257, 263, 271, 283, 293, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 389, 409, 433, 439, 457, 461, 479, 487, 509, 521, 523, 557, 563, 631, 653, 659, 673, 677, 719, 733, 739

Offset: 1

Robert Price, Dec 09 2018

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.

Robert Price, Table of n, a(n) for n = 1..304

Cf. A080608, A080603, A096235-A096246.

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[]]]];
d (* Robert Price, Dec 09 2018 *)

A322477 Base-12 deletable primes (written in base 10).

Original entry on oeis.org

2, 3, 5, 7, 11, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 79, 83, 89, 101, 103, 107, 113, 127, 131, 137, 139, 149, 151, 163, 167, 173, 179, 181, 191, 197, 199, 211, 223, 227, 229, 233, 239, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 317, 331, 347, 349, 353, 359, 367, 373, 379

Offset: 1

Robert Price, Dec 09 2018

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.

Robert Price, Table of n, a(n) for n = 1..910

Cf. A080608, A080603, A096235-A096246.

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[]]]];
d (* Robert Price, Dec 09 2018 *)

A096245 Number of n-digit base-12 deletable primes.

Original entry on oeis.org

5, 25, 186, 1398, 11500, 99074, 893062, 8352961, 80564801

Offset: 1

Michael Kleber, Feb 28 2003

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 0's in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Cf. A080608, A080603, A096235-A096246.

b = 12; a = {5}; d = {2, 3, 5, 7, 11};
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 *)

from sympy import isprime
from sympy.ntheory.digits import digits
def strmap(d):
    return str(d) if d < 10 else "ABCDEFGHIJKLMNOPQRSTUVWXYZ"[d-10]
def ok(n, prevset, base=12): # works for bases 2-36
    if not isprime(n): return False
    s = "".join(strmap(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, base=12): # works for bases 3-36
    s = set([p for p in range(1, base) if isprime(p)])
    alst, snxt = [len(s)], set()
    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(6) # Michael S. Branicky, Jan 17 2022

a(6)-a(8) from Ryan Propper, Jul 19 2005
Edited by Charles R Greathouse IV, Aug 03 2010
a(9) from Michael S. Branicky, Jan 17 2022

A125589 Smallest n-digit base-10 deletable prime.

Original entry on oeis.org

2, 13, 103, 1013, 10039, 100103, 1000193, 10000931, 100001903, 1000003957, 10000003957, 100000013957, 1000000030957, 10000000301957, 100000000730957, 1000000000730957, 10000000003632979, 100000000007309357

Offset: 1

N. J. A. Sloane, Jan 07 2007

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.

Cf. A080608, A096243, A096246, A125590.

b = 10; a = {2}; d = {2, 3, 5, 7};
For[n = 2, n <= 6, n++,
  found = False;
  p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
  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]]];
     If[! found , AppendTo[a, p[[i]]]]; found = True; Break[]]];
]]; a (* Robert Price, Nov 13 2018 *)

a(6) - a(8) from Michael Kleber, Jan 08 2007
a(9) - a(14) from Phil Carmody, Jan 09 2007
a(15) - a(18) from Joshua Zucker, Jan 09 2007

A125590 Largest n-digit base-10 deletable prime.

Original entry on oeis.org

7, 97, 997, 9973, 99929, 999907, 9999907, 99999307, 999996671, 9999996073, 99999966307, 999999908773, 9999999710639, 99999999697769, 999999997160639, 9999999996977699, 99999999980803477, 999999999961861807, 9999999999961861807, 99999999999807429133

Offset: 1

N. J. A. Sloane, Jan 07 2007

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.

			99929 -> 9929 -> 929 -> 29 -> 2.

C. Caldwell, Truncatable primes, J. Recreational Math., 19:1 (1987) 30-33. [Discusses left truncatable primes, right truncatable primes and deletable primes.]

I. O. Angell and H. J. Godwin, On Truncatable Primes, Math. Comput. 31, 265-267, 1977.
C. Caldwell, Deletable primes
Prime Curios, A 300-digit example
Carlos Rivera, Puzzle 138: Deletable Primes, Prime Puzzles and Problems Connection. [Includes a 500-digit example]
Index entries for sequences related to truncatable primes

Cf. A080608, A096243, A096246, A125589.

b = 10; a = {7}; d = {2, 3, 5, 7};
For[n = 2, n <= 5, n++,
  p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
  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]]]; Break[]]]];
  AppendTo[a, Last[d]]];
a (* Robert Price, Nov 13 2018 *)

from sympy import isprime, prevprime
from functools import cache
@cache
def deletable_prime(n):
    if not isprime(n): return False
    if n < 10: return True
    s = str(n)
    si = (s[:i]+s[i+1:] for i in range(len(s)))
    return any(t[0] != '0' and deletable_prime(int(t)) for t in si)
def a(n):
    p = prevprime(10**n)
    while not deletable_prime(p): p = prevprime(p)
    return p
print([a(n) for n in range(1, 15)]) # Michael S. Branicky, Jan 13 2022

a(6)-a(8) from Michael Kleber, Jan 08 2007
a(9)-a(16) from Joshua Zucker, May 11 2007
a(17)-a(20) from Michael S. Branicky, Jan 13 2022

A320587 Primes that are not Base-3 deletable primes (written in base 10).

Original entry on oeis.org

3, 13, 31, 37, 41, 43, 67, 79, 97, 103, 109, 113, 127, 131, 139, 149, 151, 157, 163, 193, 199, 211, 227, 229, 239, 241, 257, 271, 277, 281, 283, 293, 307, 311, 313, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 433, 439, 443

Offset: 1

Robert Price, Nov 14 2018

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 A319596.

Robert Price, Table of n, a(n) for n = 1..906

Cf. A080608, A080603, A096235-A096246.

b = 3; 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 06 2018 *)

Added the term 3. As pointed out by Kevin Ryde, there is no need to "seed" the list using base-2 assumptions. - Robert Price, Dec 06 2018

cp's OEIS Frontend

A321910 Base-7 deletable primes (written in base 10).

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A322173 Base-6 deletable primes (written in base 10).

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A322471 Base-9 deletable primes (written in base 10).

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A322474 Primes that are not base-10 deletable primes (written in base 10).

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A322475 Base-11 deletable primes (written in base 10).

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A322477 Base-12 deletable primes (written in base 10).

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A096245 Number of n-digit base-12 deletable primes.

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A125589 Smallest n-digit base-10 deletable prime.

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A125590 Largest n-digit base-10 deletable prime.

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