A019546 -id:A019546 - cp's OEIS frontend

A213307 Minimal prime with n nonprime substrings (Version 3: substrings with leading zeros are counted as nonprime if the corresponding number is not a prime).

2, 13, 11, 127, 101, 149, 1009, 1063, 1049, 1481, 10091, 10069, 10169, 11681, 14669, 100129, 100189, 100169, 101681, 104681, 146669, 1000669, 1001219, 1001081, 1004669, 1014469, 1046849, 1468469, 10001081, 10004669, 10010851

Offset: 0

Hieronymus Fischer, Aug 26 2012

			a(0) = 2, since 2 is the least number with zero nonprime substrings.
a(1) = 13, since 13 there is one nonprime substring (=1).
a(2) = 11, since 11 is the least number with 2 nonprime substrings (2 times ‘1’).
a(3) = 127, since 127 is the least number with 3 nonprime substrings, these are 1 and 12 and 27 (according to version 3).

Hieronymus Fischer, Table of n, a(n) for n = 0..100

Cf. A019546, A035232, A039996, A046034, A069489, A085823, A211681, A211682, A211684, A211685.

Cf. A035244, A079307, A213300 - A213321.

a(n) > 10^floor((sqrt(8*n+1)-1)/2), for n>2.
a(n) >= A213304(n).
a(n) >= A213306(n).

A217103 Minimal number (in decimal representation) with n nonprime substrings in base-3 representation (substrings with leading zeros are considered to be nonprime).

Original entry on oeis.org

2, 1, 3, 4, 14, 9, 34, 29, 30, 27, 89, 88, 83, 84, 81, 268, 251, 250, 248, 245, 243, 752, 754, 746, 740, 734, 731, 729, 2237, 2239, 2210, 2203, 2198, 2192, 2189, 2187, 6632, 6611, 6614, 6584, 6577, 6569, 6563, 6564, 6561, 19814, 19754, 19733, 19736, 19706

Offset: 0

Hieronymus Fischer, Dec 12 2012

The sequence is well-defined in that for each n the set of numbers with n nonprime substrings is not empty. Proof: Define m(n):=2*sum_{j=i..k} 3^j, where k:=floor((sqrt(8*n+1)-1)/2), i:= n-A000217(k). For n=0,1,2,3,… the m(n) in base-3 representation are 2, 22, 20, 222, 220, 200, 2222, 2220, 2200, 2000, 22222, 22220, .... m(n) has k+1 digits and (k-i+1) 2’s, thus, the number of nonprime substrings of m(n) is ((k+1)*(k+2)/2)-k-1+i = (k*(k+1)/2)+i = n, which proves the statement.

If p is a number with k prime substrings and d digits (in base-3 representation), p != 1 (mod 3), m>=d, than b := p*3^(m-d) has m*(m+1)/2 - k nonprime substrings, and a(A000217(n)-k) <= b.

			a(0) = 2, since 2 = 2_3 is the least number with zero nonprime substrings in base-3 representation.
a(1) = 1, since 1 = 1_3 is the least number with 1 nonprime substring in base-3 representation.
a(2) = 3, since 3 = 10_3 is the least number with 2 nonprime substrings in base-3 representation (0 and 1).
a(3) = 4, since 4 = 11_3 is the least number with 3 nonprime substrings in base-3 representation (1, 1 and 11).
a(4) = 14, since 14 = 112_3 is the least number with 4 nonprime substrings in base-3 representation, these are 1, 1, 11 and 112 (remember, that substrings with leading zeros are considered to be nonprime).
a(7) = 29, since 29 = 1002_3 is the least number with 7 nonprime substrings in base-3 representation, these are 0, 0, 1, 00, 02, 002 and 100 (remember, that substrings with leading zeros are considered to be nonprime, 2_3 = 2, 10_3 = 3 and 1002_3 = 29 are base-3 prime substrings).

Hieronymus Fischer, Table of n, a(n) for n = 0..702

Cf. A019546, A035232, A039996, A046034, A069489, A085823, A211681, A211682, A211684, A211685.
Cf. A035244, A079397, A213300-A213321.
Cf. A217102-A217109.
Cf. A217302-A217309.

a(n) >= 3^floor((sqrt(8*n-7)-1)/2) for n>0, equality holds if n=1 or n+1 is a triangular number (cf. A000217).
a(n) >= 3^floor((sqrt(8*n+1)-1)/2) for n>3, equality holds if n+1 is a triangular number.
a(A000217(n)-1) = 3^(n-1), n>1.
a(A000217(n)-k) >= 3^(n-1) + k-1, 1<=k<=n, n>1.
a(A000217(n)-k) = 3^(n-1) + p, where p is the minimal number >= 0 such that 3^(n-1) + p, has k prime substrings in base-3 representation, 1<=k<=n, n>1.

A217303 Minimal natural number (in decimal representation) with n prime substrings in base-3 representation (substrings with leading zeros are considered to be nonprime).

Original entry on oeis.org

1, 2, 5, 11, 17, 23, 50, 104, 71, 152, 215, 395, 476, 701, 719, 1367, 1934, 1448, 4127, 4121, 4346, 5822, 12302, 12383, 17468, 25505, 32066, 39113, 51749, 91040, 111509, 110798, 117359, 157211, 332396, 334358, 465092, 333791, 819386, 865232, 1001375, 1396673

Offset: 0

Hieronymus Fischer, Nov 22 2012

The sequence is well-defined in that for each n the set of numbers with n prime substrings is not empty. Proof: Define m(0):=1, m(1):=2 and m(n+1):=3*m(n)+2 for n>0. This results in m(n)=2*sum_{j=0..n-1} 3^j = 3^n - 1 or m(n)=1, 2, 22, 222, 2222, 22222, …,for n=0,1,2,3,…. Evidently, for n>0 m(n) has n 2’s and these are the only prime substrings in base-3 representation. This is why every substring of m(n) with more than one digit is a product of two integers > 1 (by definition) and can therefore not be prime number.

No term is divisible by 3.

			a(1) = 2 = 2_3, since 2 is the least number with 1 prime substring in base-3 representation.
a(2) = 5 = 12_3, since 5 is the least number with 2 prime substrings in base-3 representation (2_3 and 12_3).
a(3) = 11 = 102_3, since 11 is the least number with 3 prime substrings in base-3 representation (2_3, 10_3, and 102_3).
a(5) = 23 = 212_3, since 23 is the least number with 5 prime substrings in base-3 representation (2 times 2_3, 12_3=5, 21_3=19, and 212_3=23).
a(7) = 104 = 10212_3, since 104 is the least number with 7 prime substrings in base-3 representation (2 times 2_3, 10_3=3, 12_3=5, 21_3=19, 102_3=11, and 212_3=23).

Hieronymus Fischer, Table of n, a(n) for n = 0..110

Cf. A019546, A035232, A039996, A046034, A069489, A085823, A211681, A211682, A211684, A211685.
Cf. A035244, A079397, A213300-A213321.
Cf. A217302-A217309.

a(n) > 3^floor(sqrt(8*n+1)-1)/2), for n>1.
a(n) <= 3^n - 1.
a(n+1) <= 3a(n)+2.

A217308 Minimal natural number (in decimal representation) with n prime substrings in base-8 representation (substrings with leading zeros are considered to be nonprime).

Original entry on oeis.org

1, 2, 11, 19, 83, 107, 157, 669, 751, 1259, 4957, 6879, 6011, 14303, 47071, 48093, 65371, 188143, 327515, 440287, 384751, 1029883, 2604783, 2948955, 3602299, 6946651, 20304733, 23846747, 23937003, 23723867, 57278299, 167689071, 175479547, 191496027, 233824091

Offset: 0

Hieronymus Fischer, Nov 22 2012

The sequence is well-defined in that for each n the set of numbers with n prime substrings is not empty. Proof: Define m(0):=1, m(1):=2 and m(n+1):=8*m(n)+2 for n>0. This results in m(n)=2*sum_{j=0..n-1} 8^j = 2*(8^n - 1)/7 or m(n)=1, 2, 22, 222, 2222, 22222, …, (in base-8) for n=0,1,2,3,…. Evidently, for n>0 m(n) has n 2’s and these are the only prime substrings in base-8 representation. This is why every substring of m(n) with more than one digit is a product of two integers > 1 (by definition) and can therefore not be prime number.

No term is divisible by 8.

			a(1) = 2 = 2_8, since 2 is the least number with 1 prime substring in base-8 representation.
a(2) = 11 = 13_8, since 11 is the least number with 2 prime substrings in base-8 representation (3_8 and 13_8).
a(3) = 19 = 23_8, since 19 is the least number with 3 prime substrings in base-8 representation (2_8, 3_8, and 23_8).
a(4) = 83 = 123_8, since 83 is the least number with 4 prime substrings in base-8 representation (2_8, 3_8, 23_8=19, and 123_8=83).
a(8) = 751 = 1357_8, since 751 is the least number with 8 prime substrings in base-8 representation (3_8, 5_8, 7_8, 13_8=11, 35_8=29, 57_8=47, 357_8=239, and 1357_8=751).

Hieronymus Fischer, Table of n, a(n) for n = 0..45

Cf. A019546, A035232, A039996, A046034, A069489, A085823, A211681, A211682, A211684, A211685.
Cf. A035244, A079397, A213300-A213321.
Cf. A217302-A217309.

a(n) > 8^floor(sqrt(8*n-7)-1)/2), for n>0.
a(n) <= 2*(8^n - 1)/7, n>0.
a(n+1) <= 8*a(n)+2.

A226108 Primes remaining prime if all but two digits are deleted.

Original entry on oeis.org

11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 113, 131, 137, 173, 179, 197, 311, 317, 431, 617, 719, 1117, 1171, 4111, 11113, 11117, 11119, 11131, 11171, 11173, 11197, 11311, 11317, 11719, 11731, 13171, 13711, 41113

Offset: 1

Tim Cieplowski, May 26 2013

Subsequence of A069488.

			For a(3)=137, all pairs of two digits (in their original order) 13, 17, and 37 are prime.

C. Caldwell, Truncatable primes, J. Recreational Math., 19:1 (1987) 30-33.

Tim Cieplowski, Table of n, a(n) for n = 1..2720
P. Ballew, Knockout Primes and a new notation, May 17, 2013
C. Caldwell, The Prime Glossary: Deletable Prime

Cf. A019546, A051362, A069488.

testQ[n_] := n > 9 && Catch[Block[{d = IntegerDigits@n}, Do[If[! PrimeQ[ d[[j]] + 10*d[[i]]], Throw@False], {j, 2, Length@d}, {i, j-1}]; True]]; Select[Prime@ Range[10^5], testQ] (* Giovanni Resta, May 28 2013 *)

A082756 Larger of a pair of consecutive primes having only prime digits.

Original entry on oeis.org

3, 5, 7, 227, 733, 3257, 3733, 5237, 5333, 7577, 7727, 7757, 22277, 23333, 25537, 27737, 32237, 32327, 32537, 35327, 35537, 37273, 37277, 52237, 52733, 53327, 53353, 53777, 55337, 72227, 72733, 75227, 75533, 75557, 222533, 222553, 222557, 223277, 223757, 225227

Offset: 1

Amarnath Murthy, Apr 18 2003

			227 is a term as the previous prime 223 also has only prime digits.

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Cf. A019546, A082755.

NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; p = 0; q = 1; pd = {1}; Do[p = q; pd = qd; q = NextPrim[p]; qd = Union[ Join[{2, 3, 5, 7}, IntegerDigits[q]]]; If[pd == qd == {2, 3, 5, 7}, Print[q]], {n, 1, 20000}]
Transpose[Select[Partition[Prime[Range[20000]],2,1],And@@PrimeQ[ Flatten[ IntegerDigits/@#]]&]] [[2]] (* Harvey P. Dale, Jul 19 2011 *)

from sympy import nextprime, isprime
from itertools import count, islice, product
def onlypd(n): return set(str(n)) <= set("2357")
def agen():
    yield from [3, 5, 7]
    for digits in count(2):
        for p in product("2357", repeat=digits-1):
            for end in "37":
                t = int("".join(p) + end)
                if isprime(t):
                    t2 = nextprime(t)
                    if onlypd(t2):
                        yield t2
print(list(islice(agen(), 40))) # Michael S. Branicky, Mar 11 2022

Edited and extended by Robert G. Wilson v, Apr 22 2003

a(38) and beyond from Michael S. Branicky, Mar 11 2022

A092629 Numbers that have a nonprime number of prime digits.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 24, 26, 28, 29, 30, 31, 34, 36, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 54, 56, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 74, 76, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88

Offset: 1

Jani Melik, Apr 11 2004

			24 has one prime digit 2 and their number 1 is nonprime;
235719 has four prime digits 2,3,5,7 and their number 4 is nonprime.
313 is not in the sequence as it has a prime number (2) of prime digits (3, 3). - _David A. Corneth_, Aug 09 2023

Cf. A019546.

stev_sez:=proc(n) local i, tren, st, ans,anstren; ans:=[ ]: anstren:=[ ]: tren:=n: for i while (tren>0) do st:=round( 10*frac(tren/10) ): ans:=[ op(ans), st ]: tren:=trunc(tren/10): end do; for i from nops(ans) to 1 by -1 do anstren:=[ op(anstren), op(i,ans) ]; od; RETURN(anstren); end: ts_stpf:=proc(n) local i, stpf, ans; ans:=stev_sez(n): stpf:=0: for i from 1 to nops(ans) do if (isprime(op(i,ans))='true') then stpf:=stpf+1; # number of prime digits fi od; RETURN(stpf) end: ts_nepr:=proc(n) local i, stpf, ans, ans1; ans:=[ ]: stpf:=0: for i from 1 to n do if (isprime( ts_stpf(i) )='false') then ans:=[ op(ans), i ]: fi od; RETURN(ans) end: ts_nepr(600);

Select[Range[100],!PrimeQ[Count[IntegerDigits[#],?PrimeQ]]&] (* _Harvey P. Dale, Jan 15 2013 *)

Edited by Charles R Greathouse IV, Aug 03 2010

A113590 Least multiple of prime(n) containing only prime digits (2,3,5,7).

Original entry on oeis.org

2, 3, 5, 7, 22, 52, 255, 57, 23, 232, 372, 37, 533, 2322, 235, 53, 2537, 732, 335, 355, 73, 237, 332, 2225, 2522, 2222, 2575, 535, 327, 2373, 22225, 2227, 7535, 3753, 2235, 755, 2355, 7335, 27555, 23355, 537, 2353, 573, 772, 27777, 5373, 2532, 223, 227, 5725, 233

Offset: 1

Amarnath Murthy, Nov 07 2005

a(n) = prime(n) if prime(n) is in A019546.

Robert Israel, Table of n, a(n) for n = 1..10000

Cf. A019546, A113591.

N:= 100: # to get a(1)..a(N)
pn:= ithprime(N):
count:= 0:
digs:= [2,3,5,7]:
for d from 1 while count < N do
for m from 4^d to 2*4^d-1 while count < N do
  L:= convert(m,base,4);
  n:= add(digs[L[i]+1]*10^(i-1),i=1..nops(L)-1);
  ps:= select(p -> p <= pn and not assigned(A[p]), numtheory:-factorset(n));
  count:= count + nops(ps);
  for p in ps do A[p]:= n od:
od od:
seq(A[ithprime(i)],i=1..N); # Robert Israel, Dec 27 2018

More terms from Nick Woods (njw130(AT)psu.edu), Apr 25 2006

a(44) and a(50) corrected by Robert Israel, Dec 27 2018

A152426 Primes that have both prime digits (2,3,5,7) and nonprime digits (0,1,4,6,8,9).

Original entry on oeis.org

13, 17, 29, 31, 43, 47, 59, 67, 71, 79, 83, 97, 103, 107, 113, 127, 131, 137, 139, 151, 157, 163, 167, 173, 179, 193, 197, 211, 229, 239, 241, 251, 263, 269, 271, 281, 283, 293, 307, 311, 313, 317, 331, 347, 349, 359, 367, 379

Offset: 1

Omar E. Pol, Dec 03 2008

See also A152427, a subsequence without zeros.

Cf. A019546, A034844, A087363, A092621, A092626, A152312, A152313, A152427.

okQ[n_] := Module[{d=Union[IntegerDigits[n]]}, Length[Intersection[d, {2,3,5,7}]]>0 && Length[Intersection[d, {0,1,4,6,8,9}]]>0]; Select[Prime[Range[100]], okQ] (* T. D. Noe, Jan 20 2011 *)

Edited by Omar E. Pol, Jul 04 2009, Jan 20 2011

Definition clarified by N. J. A. Sloane, Jul 05 2009

A152427 Primes that have both prime digits (2,3,5,7) and nonprime digits (1,4,6,8,9).

Original entry on oeis.org

13, 17, 29, 31, 43, 47, 59, 67, 71, 79, 83, 97, 103, 107, 113, 127, 131, 137, 139, 151, 157, 163, 167, 173, 179, 193, 197, 211, 229, 239, 241, 251, 263, 269, 271, 281, 283, 293, 311, 313, 317, 331, 347, 349, 359, 367, 379, 383, 389, 397, 421, 431, 433, 439

Offset: 1

Omar E. Pol, Dec 03 2008

A000040 \ A034844 \ A019546.

Cf. A018252.

Cf. A018252, A019546, A034844, A087363, A092621, A092626, A152312, A152313, A152426.

okQ[n_] := Module[{d = Union[IntegerDigits[n]]}, Length[Intersection[d, {2, 3, 5, 7}]] > 0 && Length[Intersection[d, {1, 4, 6, 8, 9}]] > 0]; Select[Prime[Range[100]], okQ] (* T. D. Noe, Jan 21 2011 *)
pdQ[n_]:=Module[{idn=Select[IntegerDigits[n],#!=0&]},Count[idn,?PrimeQ]>0&&Count[idn,?(!PrimeQ[#]&)]>0]; Select[Prime[Range[100]],pdQ] (* Harvey P. Dale, Jan 31 2013 *)

a(n) ~ n log n

Corrected and extended by Harvey P. Dale, Jan 31 2013

cp's OEIS Frontend

A213307 Minimal prime with n nonprime substrings (Version 3: substrings with leading zeros are counted as nonprime if the corresponding number is not a prime).

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A217103 Minimal number (in decimal representation) with n nonprime substrings in base-3 representation (substrings with leading zeros are considered to be nonprime).

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A217303 Minimal natural number (in decimal representation) with n prime substrings in base-3 representation (substrings with leading zeros are considered to be nonprime).

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A217308 Minimal natural number (in decimal representation) with n prime substrings in base-8 representation (substrings with leading zeros are considered to be nonprime).

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A226108 Primes remaining prime if all but two digits are deleted.

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Mathematica

A082756 Larger of a pair of consecutive primes having only prime digits.

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Mathematica

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A092629 Numbers that have a nonprime number of prime digits.

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Maple

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A113590 Least multiple of prime(n) containing only prime digits (2,3,5,7).

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Maple

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A152426 Primes that have both prime digits (2,3,5,7) and nonprime digits (0,1,4,6,8,9).

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