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 1-5 of 5 results.

A217039 Primes having only {4, 5, 7} as digits.

Original entry on oeis.org

5, 7, 47, 457, 547, 557, 577, 757, 4447, 4457, 4547, 5477, 5557, 7457, 7477, 7547, 7577, 7757, 44777, 45557, 45757, 47777, 54547, 54577, 55457, 55547, 57457, 57557, 74747, 75557, 75577, 77447, 77477, 77557, 77747, 444547, 444557, 445447, 445477, 445747, 447757
Offset: 1

Views

Author

Jonathan Vos Post, Sep 24 2012

Keywords

Comments

These are the primes in A214584. Primes whose numerals are all written (san serif) with at least one right or acute angle.

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(450000) | Intseq(p) subset [4,5,7]]; // Bruno Berselli, Sep 25 2012
    
  • Mathematica
    Select[Flatten[Table[FromDigits/@Tuples[{4,5,7},n],{n,6}]],PrimeQ] (* Bruno Berselli, Sep 25 2012 *)
  • PARI
    A217039(n=50,show=0,L=[4,5,7])={for(d=1,1e9, my(t, u=vector(d,i,10^(d-i))~); forvec(v=vector(d,i,[if(i==d&&d>1,3/*must end in 7*/,1), #L]), ispseudoprime(t=vecextract(L, v)*u)||next; show&&print1(t", "); n--||return(t)))} \\ Syntax updated for newer PARI versions by M. F. Hasler, Jul 25 2015

Formula

A000040 INTERSECTION A214584.

A034470 Prime numbers using only the curved digits 0, 2, 3, 5, 6, 8 and 9.

Original entry on oeis.org

2, 3, 5, 23, 29, 53, 59, 83, 89, 223, 229, 233, 239, 263, 269, 283, 293, 353, 359, 383, 389, 503, 509, 523, 563, 569, 593, 599, 653, 659, 683, 809, 823, 829, 839, 853, 859, 863, 883, 929, 953, 983, 2003, 2029, 2039, 2053, 2063, 2069, 2083, 2089, 2099, 2203
Offset: 1

Views

Author

Robert G. Wilson v, Jan 24 2003

Keywords

Comments

Intersection of A000040 and A028374. - K. D. Bajpai, Sep 07 2014

Examples

			From _K. D. Bajpai_, Sep 07 2014: (Start)
29 is prime and is composed only of the curved digits 2 and 9.
359 is prime and is composed only of the curved digits 3, 5 and 9.
(End)
20235869 is the smallest instance using all curved digits. - _Michel Marcus_, Sep 07 2014
		

Crossrefs

Programs

  • Maple
    N:= 4: # to get all entries with at most N digits
    S:= {0,2,3,5,6,8,9}:
    T:= S:
    for j from 2 to N do
    T:= map(t -> seq(10*t+s,s=S),T);
    od:
    select(isprime,T);
    # In Maple 11 and earlier, uncomment the next line:
    # sort(convert(%,list)); # Robert Israel, Sep 07 2014
  • Mathematica
    Select[Range[2222], PrimeQ[#] && Union[Join[IntegerDigits[#], {0, 2, 3, 5, 6, 8, 9}]] == {0, 2, 3, 5, 6, 8, 9} &] (* RGWv *)
    Select[Prime[Range[500]], Intersection[IntegerDigits[#], {1, 4, 7}] == {} &] (* K. D. Bajpai, Sep 07 2014 *)

A361822 Primes without {2, 5} as digits.

Original entry on oeis.org

3, 7, 11, 13, 17, 19, 31, 37, 41, 43, 47, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 163, 167, 173, 179, 181, 191, 193, 197, 199, 307, 311, 313, 317, 331, 337, 347, 349, 367, 373, 379, 383, 389, 397, 401, 409, 419, 431, 433, 439, 443, 449, 461, 463
Offset: 1

Views

Author

Bernard Schott, Mar 26 2023

Keywords

Comments

Subsequence of primes that are in A361780.

Crossrefs

Intersection of A000040 and A361780.
Cf. A079651 (primes with {1, 4, 7}), A079652 (primes with {0, 3, 6, 8, 9}).
Cf. A247052 (primes with {1, 2, 4, 5, 7}), A034470 (primes with {0, 2, 3, 5, 6, 8, 9}).
Cf. A106116, A154761, A386320 - A386358 (primes without two decimal digits).
Cf. A385776.

Programs

  • Maple
    filter:= proc(n) convert(convert(n,base,10),set) intersect {2,5} = {} end proc:
    select(filter, [seq(ithprime(i),i=1..1000)]); # Robert Israel, Mar 26 2023
  • Mathematica
    Select[Prime[Range[100]], AllTrue[IntegerDigits[#], ! MemberQ[{2, 5}, #1] &] &] (* Amiram Eldar, Mar 26 2023 *)
  • Python
    print(list(islice(primes_with("01346789"), 41))) # uses function/imports in A385776. Jason Bard, Jul 20 2025

A217048 Semiprimes using only the curved digits 0, 3, 6, 8 and 9.

Original entry on oeis.org

6, 9, 33, 38, 39, 69, 86, 93, 303, 309, 339, 386, 393, 398, 633, 669, 689, 698, 699, 803, 838, 866, 869, 886, 889, 893, 898, 899, 933, 939, 989, 993, 998, 3039, 3063, 3086, 3093, 3098, 3099, 3309, 3338, 3369, 3383, 3386, 3398, 3603, 3639, 3669, 3683, 3693
Offset: 1

Views

Author

Jonathan Vos Post, Sep 25 2012

Keywords

Comments

This is to A079652 as semiprimes A001358 are to primes A000040.

Examples

			a(41) = 3338 = 2 * 1669, the 938th semiprime.
		

Crossrefs

Programs

  • Magma
    IsSemiprime:=func; [n: n in [2..3700] | IsSemiprime(n) and Intseq(n) subset [0,3,6,8,9]]; // Bruno Berselli, Sep 25 2012
  • Maple
    R:= [0,3,6,8,9]:
    Res:= NULL: count:= 0:
    for m from 1 while count < 100 do
      L:= convert(m,base,5);
      n:= add(R[L[i]+1]*10^(i-1),i=1..nops(L));
      if numtheory:-bigomega(n)=2 then Res:= Res, n; count:= count+1 fi
    od:
    Res; # Robert Israel, Feb 16 2020

Formula

A001358 INTERSECTION A072960.

A107291 Numbers k such that 10^k*(10^7*(-1+10^k)+6083806) + 10^k - 1 is prime.

Original entry on oeis.org

8, 33, 41, 495, 657, 1904, 4497, 9369, 11096, 11465, 12542, 20819
Offset: 1

Views

Author

Jason Earls, May 20 2005

Keywords

Comments

These are palprimes with curved digits, i.e., palindromic primes composed of only 0's, 3s, 6s, 8s, or 9s and they have all been proved prime. No more terms up to 7000. Primality proof for the largest: PFGW Version 20041001.Win_Stable (v1.2 RC1b) [FFT v23.8] Primality testing 10^4497*(10^7*(-1+10^4497)+6083806)+10^4497-1 [N+1, Brillhart-Lehmer-Selfridge] Running N+1 test using discriminant 3, base 1+sqrt(3) Running N+1 test using discriminant 3, base 3+sqrt(3) Running N+1 test using discriminant 3, base 5+sqrt(3) 10^4497*(10^7*(-1+10^4497)+6083806)+10^4497-1 is prime! (147.0046s+0.0074s)

Examples

			8 is a term because 10^8*(10^7*(-1+10^8)+6083806)+10^8-1 = 99999999608380699999999 is prime.
		

Crossrefs

Cf. A079652.

Programs

Extensions

a(8)-a(12) from Michael S. Branicky, Sep 21 2024
Showing 1-5 of 5 results.