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 1-4 of 4 results.

A020459 Primes that contain digits 2 and 7 only.

Original entry on oeis.org

2, 7, 227, 277, 727, 2777, 7727, 22277, 22727, 22777, 27277, 72227, 72277, 72727, 272227, 272777, 727777, 777277, 2227727, 2227777, 2272727, 2277727, 2727727, 2772227, 7272227, 7722277, 7727777, 7772777, 7777727, 22227277, 22272277
Offset: 1

Views

Author

David W. Wilson

Keywords

Links

Crossrefs

Cf. A000040, A284921, A329760.

Programs

  • Magma
    [p: p in PrimesUpTo(22272277) | Set(Intseq(p)) subset [2, 7]]; // Vincenzo Librandi, Jul 27 2012
  • Mathematica
    Flatten[Table[Select[FromDigits/@Tuples[{2,7},n],PrimeQ],{n,8}]] (* Vincenzo Librandi, Jul 27 2012 *)

A380906 Primes without {3, 5} as digits.

Original entry on oeis.org

2, 7, 11, 17, 19, 29, 41, 47, 61, 67, 71, 79, 89, 97, 101, 107, 109, 127, 149, 167, 179, 181, 191, 197, 199, 211, 227, 229, 241, 269, 271, 277, 281, 401, 409, 419, 421, 449, 461, 467, 479, 487, 491, 499, 601, 607, 617, 619, 641, 647, 661, 677, 691, 701, 709, 719, 727, 761, 769, 787, 797
Offset: 1

Views

Author

Vincenzo Librandi, Feb 09 2025

Keywords

Links

Crossrefs

Intersection of A038611 and A038613.
Cf. A000040, A020462, A329760.

Programs

  • Magma
    [p: p in PrimesUpTo(700) | not 3 in Intseq(p) and not 5 in Intseq(p) ];
  • Mathematica
    Select[Prime[Range[120]],DigitCount[#,10,3]==0&&DigitCount[#,10,5]==0&]
  • PARI
    isok(p) = if (isprime(p), my(d=digits(p)); (#select(x->(x==3), d)==0) && (#select(x->(x==5), d)==0)); \\ Michel Marcus, Feb 10 2025
  • Python
    from itertools import count, islice
from sympy import isprime
def A380906_gen(): # generator of terms
    return filter(isprime,(int(oct(n)[2:].translate({51:52,52:54,53:55,54:56,55:57})) for n in count(1)))
A380906_list = list(islice(A380906_gen(),20)) # Chai Wah Wu, Feb 12 2025

A386337 Primes without {2, 6} as digits.

Original entry on oeis.org

3, 5, 7, 11, 13, 17, 19, 31, 37, 41, 43, 47, 53, 59, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 151, 157, 173, 179, 181, 191, 193, 197, 199, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 373, 379, 383, 389, 397, 401, 409, 419, 431
Offset: 1

Views

Author

Jason Bard, Jul 19 2025

Keywords

Links

Crossrefs

Intersection of A038604 and A038614.
Cf. A000040, A329760, A361822, A385776.

Programs

  • Magma
    [p: p in PrimesUpTo(10^6) | Set(Intseq(p)) subset [0, 1, 3, 4, 5, 7, 8, 9]];
  • Maple
    f:= n-> (l-> add([0, 1, $3..5, $7..9][l[j]+1]*10^(j-1), j=1..nops(l)))(convert(n, base, 8)):
select(isprime, [seq(f(i), i=0..600)])[];  # Alois P. Heinz, Jul 19 2025
  • Mathematica
    Select[Prime[Range[120]], DigitCount[#, 10, 2] == 0 && DigitCount[#, 10, 6] == 0 &]
  • PARI
    primes_with(, 1, [0, 1, 3, 4, 5, 7, 8, 9]) \\ uses function in A385776
  • Python
    print(list(islice(primes_with("01345789"), 41))) # uses function/imports in A385776

A386338 Primes without {2, 8} as digits.

Original entry on oeis.org

3, 5, 7, 11, 13, 17, 19, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 97, 101, 103, 107, 109, 113, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 191, 193, 197, 199, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 397, 401, 409, 419, 431
Offset: 1

Views

Author

Jason Bard, Jul 19 2025

Keywords

Links

Crossrefs

Intersection of A038604 and A038616.
Cf. A000040, A329760, A385776.

Programs

  • Magma
    [p: p in PrimesUpTo(10^6) | Set(Intseq(p)) subset [0, 1, 3, 4, 5, 6, 7, 9]];
  • Maple
    f:= n-> (l-> add([0, 1, $3..7, 9][l[j]+1]*10^(j-1), j=1..nops(l)))(convert(n, base, 8)):
select(isprime, [seq(f(i), i=0..600)])[];  # Alois P. Heinz, Jul 19 2025
  • Mathematica
    Select[Prime[Range[120]], DigitCount[#, 10, 2] == 0 && DigitCount[#, 10, 8] == 0 &]
  • PARI
    primes_with(, 1, [0, 1, 3, 4, 5, 6, 7, 9]) \\ uses function in A385776
  • Python
    print(list(islice(primes_with("01345679"), 41))) # uses function/imports in A385776
Showing 1-4 of 4 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.