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 1-3 of 3 results.

A323391 Primes containing nonprime digits (from 1 to 9) in their decimal expansion and whose digits are distinct, i.e., consisting of only digits 1, 4, 6, 8, 9.

Original entry on oeis.org

19, 41, 61, 89, 149, 419, 461, 491, 619, 641, 691, 941, 1489, 4691, 4861, 6481, 6491, 6841, 8419, 8461, 8641, 8941, 9461, 14869, 46819, 48619, 49681, 64189, 64891, 68491, 69481, 81649, 84691, 84961, 86491, 98641
Offset: 1

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Author

Bernard Schott, Jan 13 2019

Keywords

Comments

There are only 36 terms in this sequence, which is a finite subsequence of A152313.
Two particular examples:
6481 is also the smallest prime formed from the concatenation of two consecutive squares.
81649 is the only prime containing all the nonprime positive digits such that every string of two consecutive digits is a square.

Examples

			14869 is the smallest prime that contains all the nonprime positive digits; 98641 is the largest one.
		

Crossrefs

Subsequence of A152313. Subsequence of A029743. Subsequence of A155024 (with distinct nonprime digits but with 0) and of A034844.
Cf. A029743 (with distinct digits), A124674 (with distinct prime digits), A155045 (with distinct odd digits), A323387 (with distinct square digits), A323578 (with distinct digits for which parity of digits alternates).

Programs

  • Mathematica
    Select[Union@ Flatten@ Map[FromDigits /@ Permutations@ # &, Rest@ Subsets@ {1, 4, 6, 8, 9}], PrimeQ] (* Michael De Vlieger, Jan 19 2019 *)
  • PARI
    isok(p) = isprime(p) && (d=digits(p)) && vecmin(d) && (#Set(d) == #d) && (#select(x->isprime(x), d) == 0); \\ Michel Marcus, Jan 14 2019

A331346 Primes using all the square digits {0, 1, 4, 9} and no others.

Original entry on oeis.org

1049, 1409, 4019, 4091, 9041, 10499, 10949, 14009, 49019, 49109, 90149, 90401, 94109, 99041, 99401, 100049, 101149, 101419, 101449, 104009, 104119, 104149, 104491, 104911, 104999, 109049, 109141, 109441, 110419, 110491, 111049, 111409, 114901, 140009, 140191, 140419
Offset: 1

Views

Author

K. D. Bajpai, Jan 14 2020

Keywords

Comments

Subsequence of A061246.

Examples

			a(1) = 1049 is prime containing all the square digits (0, 1, 4, 9) and no others.
a(2) = 1409 is prime containing all the square digits (0, 1, 4, 9) and no others.
		

Crossrefs

Programs

  • Magma
    [p:p in PrimesUpTo(150000)|Set(Intseq(p)) eq {0,1,4,9}]; // Marius A. Burtea, Jan 14 2020
  • Maple
    f:= proc(n) local L,x;
      L:= convert(n,base,4);
      if convert(L,set) <> {0,1,2,3} then return NULL fi;
      L:= subs(2=4,3=9,L);
      x:= add(L[i]*10^(i-1),i=1..nops(L));
      if isprime(x) then x else NULL fi
    end proc:
    map(f, [$4^3..4^6]); # Robert Israel, Jan 16 2020
  • Mathematica
    Select[FromDigits /@ Tuples[{0, 1, 4, 9}, 6], PrimeQ[#] && Union[IntegerDigits[#]] == {0, 1, 4, 9} &]

A323579 Primes formed by using the four terminal digits of multidigit primes and whose digits are distinct, i.e., consisting of only digits 1, 3, 7, 9.

Original entry on oeis.org

3, 7, 13, 17, 19, 31, 37, 71, 73, 79, 97, 137, 139, 173, 179, 193, 197, 317, 379, 397, 719, 739, 937, 971, 1973, 3719, 3917, 7193, 9137, 9173, 9371
Offset: 1

Views

Author

Bernard Schott, Jan 24 2019

Keywords

Comments

There are only 31 terms in this sequence, which is a finite subsequence of A091633 and of A155045.
719 is also the third factorial prime belonging to A055490.

Examples

			1973 and 9371 are respectively the smallest and the largest primes formed with the four digits that can end multidigit primes.
		

Crossrefs

Subsequence of A091633 and hence of A030096.
Cf. A029743 (with distinct digits), A124674 (with distinct prime digits), A155024 (with distinct nonprime digits but with 0), A155045 (with distinct odd digits), A323387 (with distinct square digits), A323391 (with distinct nonprime digits), A323578 (with distinct digits for which parity of digits alternates).

Programs

  • Mathematica
    With[{w = Select[Range@ 10, GCD[#, 10] == 1 &]}, Select[FromDigits /@ Permutations[w, Length@ w], PrimeQ]] (* Michael De Vlieger, Feb 03 2019 *)
    Select[FromDigits/@Flatten[Permutations/@Subsets[{1,3,7,9}],1],PrimeQ]//Union (* Harvey P. Dale, Apr 20 2025 *)
Showing 1-3 of 3 results.