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 1-10 of 13 results. Next

A199349 Primes having only {3, 4, 9} as digits.

Original entry on oeis.org

3, 43, 349, 433, 439, 443, 449, 499, 3343, 3433, 3449, 3499, 3943, 4339, 4349, 4493, 4933, 4943, 4993, 4999, 9343, 9349, 9433, 9439, 9949, 33343, 33349, 33493, 34439, 34499, 34939, 34949, 39343, 39439, 39443, 39499, 43399, 43499, 43933, 43943, 44449, 44939, 49333, 49339, 49393, 49433, 49499, 49939, 49943, 49993
Offset: 1

Views

Author

M. F. Hasler, Nov 05 2011

Keywords

Comments

A020461 and A020466 are subsequences. - Vincenzo Librandi, Jul 30 2015

Crossrefs

Cf. Primes that contain only the digits (3,4,k): A199340 (k=0), A199341 (k=1), A199342 (k=2), A199345 (k=5), A199346 (k=6), A199347 (k=7), A199348 (k=8).

Programs

  • Magma
    [p: p in PrimesUpTo(2*10^5) | Set(Intseq(p)) subset [3, 4, 9]]; // Vincenzo Librandi, Jul 30 2015
  • Mathematica
    Select[Prime[Range[2 10^4]], Complement[IntegerDigits[#], {3, 4, 9}]=={} &] (* Vincenzo Librandi, Jul 30 2015 *)
    Select[Flatten[Table[FromDigits/@Tuples[{3,4,9},n],{n,5}]],PrimeQ] (* Harvey P. Dale, May 02 2023 *)
  • PARI
    a(n, list=0, L=[3,4,9], reqpal=0)={my(t); for(d=1, 1e9, u=vector(d, i, 10^(d-i))~; forvec(v=vector(d, i, [1+(i==1&!L[1]), #L]), isprime(t=vecextract(L,v)*u) || next; reqpal && !isprime(A004086(t)) && next; list && print1(t", "); n--||return(t)))}
    

A107666 Primes having only {4, 6, 9} as digits.

Original entry on oeis.org

449, 499, 4649, 4969, 4999, 6449, 6469, 6949, 9649, 9949, 44449, 44699, 46499, 46649, 49499, 49669, 49999, 64499, 64969, 66449, 66499, 66949, 69499, 94649, 94949, 94999, 96469, 99469, 444449, 444469, 444649, 446969, 449699, 464699, 464999, 466649, 469649, 469969
Offset: 1

Views

Author

Rick L. Shepherd, May 19 2005

Keywords

Comments

Intersection of A000040 and A107665. - K. D. Bajpai, Sep 08 2014

Examples

			From _K. D. Bajpai_, Sep 08 2014: (Start)
4649 is a term because it is a prime having only semiprime digits 4, 6 and 9.
6469 is a term because it is a prime having only semiprime digits 4, 6 and 9.
449 is the smallest prime comprising only semiprime digits 4, 6 or 9.
(End)
		

Crossrefs

Cf. A107665 (numbers with semiprime digits), A001358 (semiprimes), A051416 (primes whose digits are all composite), A020466 (primes with digits 4 and 9 only), A093402 (primes of form 44...9), A093945 (primes of form 499...).

Programs

  • Maple
    N:= 4:  Dgts:= {4, 6, 9}:  A:= NULL:
    for d from 1 to N do
    K:= combinat[cartprod]([Dgts minus {0}, Dgts $(d-1)]);
    while not K[finished] do L:= K[nextvalue]();  x:= add(L[i]*10^(d-i), i=1..d);
    if isprime(x) then A:= A, x fi od od: A;  # K. D. Bajpai, Sep 08 2014
  • Mathematica
    Select[Prime[Range[50000]], Intersection[IntegerDigits[#], {0, 1, 2, 3, 5, 7, 8}] == {} &] (* K. D. Bajpai, Sep 08 2014 *)

Extensions

a(35)-a(38) from K. D. Bajpai, Sep 08 2014

A260271 Primes having only {1, 4, 9} as digits.

Original entry on oeis.org

11, 19, 41, 149, 191, 199, 419, 449, 491, 499, 911, 919, 941, 991, 1499, 1949, 1999, 4111, 4441, 4919, 4999, 9199, 9419, 9491, 9941, 9949, 11119, 11149, 11411, 11491, 11941, 14149, 14411, 14419, 14449, 19141, 19441, 19919, 19949, 19991, 41141, 41149, 41411
Offset: 1

Views

Author

Vincenzo Librandi, Jul 23 2015

Keywords

Comments

A020452, A020457 and A020466 are subsequences.

Crossrefs

Cf. similar sequences listed in A260266.

Programs

  • Magma
    [p: p in PrimesUpTo(5*10^4) | Set(Intseq(p)) subset [1, 4, 9]];
  • Mathematica
    Select[Prime[Range[5 10^3]], Complement[IntegerDigits[#], {1, 4, 9}]=={} &]

A385768 Primes having only {0, 4, 9} as digits.

Original entry on oeis.org

409, 449, 499, 4049, 4099, 4409, 4909, 4999, 9049, 9949, 40009, 40099, 40499, 40949, 44449, 44909, 49009, 49409, 49499, 49999, 90499, 94009, 94049, 94099, 94949, 94999, 99409, 400009, 400409, 400949, 404009, 404099, 404449, 409099, 409499, 409909, 409999
Offset: 1

Views

Author

Jason Bard, Jul 09 2025

Keywords

Examples

			4099 is a term because it is prime, and it only contains {0,4,9}.
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(10^6) | Set(Intseq(p)) subset [0, 4, 9]];
    
  • Mathematica
    Select[FromDigits/@Tuples[{0,4,9},5],PrimeQ]
  • PARI
    primes_with(, 1, [0, 4, 9]) \\ uses function in A385776
  • Python
    print(list(islice(primes_with("049"), 41))) # uses function/imports in A385776
    

A261183 Primes having only {4, 7, 9} as digits.

Original entry on oeis.org

7, 47, 79, 97, 449, 479, 499, 797, 947, 977, 997, 4447, 4799, 4999, 7477, 7499, 7949, 9479, 9497, 9749, 9949, 44449, 44497, 44777, 44797, 47497, 47777, 47779, 47797, 47947, 47977, 49477, 49499, 49747, 49999, 74449, 74747, 74779, 74797, 77447, 77477, 77479
Offset: 1

Views

Author

Vincenzo Librandi, Aug 11 2015

Keywords

Comments

A020465, A020466 and A020471 are subsequences.

Crossrefs

Cf. similar sequences listed in A261181.

Programs

  • Magma
    [p: p in PrimesUpTo(2*10^5) | Set(Intseq(p)) subset [4, 7, 9]];
  • Mathematica
    Select[Prime[Range[6 10^4]], Complement[IntegerDigits[#], {4, 7, 9}] == {} &]

A385785 Primes having only {2, 4, 9} as digits.

Original entry on oeis.org

2, 29, 229, 449, 499, 929, 2999, 4229, 4999, 9929, 9949, 22229, 24229, 24499, 29429, 42299, 42499, 42929, 44249, 44449, 49429, 49499, 49999, 94229, 94949, 94999, 99929, 222499, 224299, 224429, 224449, 224929, 229249, 229499, 229949, 242449, 242999, 244429
Offset: 1

Views

Author

Jason Bard, Jul 13 2025

Keywords

Crossrefs

Supersequence of A020460, A020466.

Programs

  • Magma
    [p: p in PrimesUpTo(10^6) | Set(Intseq(p)) subset [2, 4, 9]];
    
  • Mathematica
    Flatten[Table[Select[FromDigits /@ Tuples[{2, 4, 9}, n], PrimeQ], {n, 7}]]
  • PARI
    primes_with(, 1, [2, 4, 9]) \\ uses function in A385776
  • Python
    print(list(islice(primes_with("249"), 41))) # uses function/imports in A385776
    

A385793 Primes having only {4, 5, 9} as digits.

Original entry on oeis.org

5, 59, 449, 499, 599, 4549, 4999, 5449, 9949, 44449, 44549, 44959, 45599, 45949, 45959, 49459, 49499, 49549, 49559, 49999, 54449, 54499, 54559, 54949, 54959, 55949, 59999, 94559, 94949, 94999, 95549, 95959, 99559, 444449, 445499, 449459, 449549, 449959, 455599
Offset: 1

Views

Author

Jason Bard, Jul 13 2025

Keywords

Crossrefs

Supersequence of A020466, A020468.

Programs

  • Magma
    [p: p in PrimesUpTo(10^6) | Set(Intseq(p)) subset [4, 5, 9]];
    
  • Mathematica
    Flatten[Table[Select[FromDigits /@ Tuples[{4, 5, 9}, n], PrimeQ], {n, 7}]]
  • PARI
    primes_with(, 1, [4, 5, 9]) \\ uses function in A385776
  • Python
    print(list(islice(primes_with("459"), 41))) # uses function/imports in A385776
    

A385796 Primes having only {4, 8, 9} as digits.

Original entry on oeis.org

89, 449, 499, 4889, 4999, 8849, 8999, 9949, 44449, 48449, 48889, 48989, 49499, 49999, 84449, 84499, 88499, 89449, 89849, 89899, 89989, 94849, 94889, 94949, 94999, 98849, 98899, 98999, 99989, 444449, 448999, 449989, 484489, 484999, 489449, 489989, 494849, 494899
Offset: 1

Views

Author

Jason Bard, Jul 13 2025

Keywords

Crossrefs

Subsequence of A030433.
Supersequence of A020466, A020472.

Programs

  • Magma
    [p: p in PrimesUpTo(10^6) | Set(Intseq(p)) subset [4, 8, 9]];
    
  • Mathematica
    Flatten[Table[Select[FromDigits /@ Tuples[{4, 8, 9}, n], PrimeQ], {n, 7}]]
  • PARI
    primes_with(, 1, [4, 8, 9]) \\ uses function in A385776
  • Python
    print(list(islice(primes_with("489"), 41))) # uses function/imports in A385776
    

A284973 Numbers with digits 4 and 9 only.

Original entry on oeis.org

4, 9, 44, 49, 94, 99, 444, 449, 494, 499, 944, 949, 994, 999, 4444, 4449, 4494, 4499, 4944, 4949, 4994, 4999, 9444, 9449, 9494, 9499, 9944, 9949, 9994, 9999, 44444, 44449, 44494, 44499, 44944, 44949, 44994, 44999, 49444, 49449, 49494, 49499, 49944, 49949
Offset: 1

Views

Author

Jaroslav Krizek, Apr 07 2017

Keywords

Crossrefs

Prime terms are in A020466.
Numbers with digits 4 and k only for k = 0 - 3 and 5 - 9: A169967 (k = 0), A032822 (k = 1), A284920 (k = 2), A032834 (k = 3), A256290 (k = 5), A284634 (k = 6), A284971 (k = 7), A284972 (k = 8), this sequence (k = 9).

Programs

  • Magma
    [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {4, 9}]
    
  • PARI
    a(n,{p=[4,9]})={my(v=binary(n+1));fromdigits(vector(#v-1,i,p[2]*v[i+1]+p[1]*!v[i+1]))} \\ R. J. Cano, Apr 09 2017

A036319 Composite numbers whose prime factors have no digits other than 4's and 9's.

Original entry on oeis.org

201601, 224051, 249001, 2244551, 2494501, 4467101, 4964551, 19957601, 22180051, 22225051, 22449551, 24700001, 24949501, 24990001, 42632101, 42654551, 47379551, 47404501, 49735051, 90518849, 98982601, 100598899, 111801449, 124251499, 199557601, 221780051, 222200551, 247445501
Offset: 1

Views

Author

Patrick De Geest, Dec 15 1998

Keywords

Comments

Closed under multiplication. - David A. Corneth, Sep 21 2020
From M. F. Hasler, Sep 22 2020: (Start)
Also closed under LCM, but not under GCD.
All terms are congruent to 1 or 9 (mod 10), depending on the parity of their number of prime factors counted with multiplicity, A001222. (End)

Examples

			The smallest prime made up of 4's and 9's is 449 (see A020466), so the smallest term here is 449^2 = 201601. - _N. J. A. Sloane_, Sep 21 2020
		

Crossrefs

Programs

  • Mathematica
    cn49Q[n_]:=Module[{fi=FactorInteger[n][[All,1]]},CompositeQ[n]&&Union[ Flatten[ IntegerDigits/@fi]]=={4,9}&&AllTrue[fi,PrimeQ]]; Select[Range[ 1,1006*10^5,2],cn49Q] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 21 2020 *)
  • PARI
    is(N)={!isprime(N)&& !#setminus(Set(concat(apply (digits, factor(N)[,1]))), [4,9])} \\ M. F. Hasler, Sep 22 2020

Formula

Sum_{n>=1} 1/a(n) = Product_{p in A020466} (p/(p - 1)) - Sum_{p in A020466} 1/p - 1 = 0.00001523788893... . - Amiram Eldar, May 22 2022

Extensions

More terms from David A. Corneth, Sep 21 2020
Showing 1-10 of 13 results. Next