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.

A139053 Array read by rows: row n lists the first 3 primes with n digits.

Original entry on oeis.org

2, 3, 5, 11, 13, 17, 101, 103, 107, 1009, 1013, 1019, 10007, 10009, 10037, 100003, 100019, 100043, 1000003, 1000033, 1000037, 10000019, 10000079, 10000103, 100000007, 100000037, 100000039, 1000000007, 1000000009, 1000000021, 10000000019, 10000000033, 10000000061
Offset: 1

Views

Author

Omar E. Pol, Apr 08 2008

Keywords

Crossrefs

Programs

  • Mathematica
    np[n_]:=Module[{a=NextPrime[10^n]},{a,NextPrime[a], NextPrime[NextPrime[ a]]}]; Flatten[Array[np,12,0]] (* Harvey P. Dale, Dec 14 2011 *)
    Flatten@Array[NextPrime[10^#,{1,2,3}]&,12,0] (* Giorgos Kalogeropoulos, May 06 2019 *)
  • Python
    from sympy import nextprime
    def auptodigs(maxdigits):
      alst = []
      for n in range(1, maxdigits+1):
        p1 = nextprime(10**(n-1))
        p2 = nextprime(p1)
        p3 = nextprime(p2)
        alst.extend([p1, p2, p3])
      return alst
    print(auptodigs(11)) # Michael S. Branicky, May 07 2021

Extensions

More terms from Max Alekseyev, Dec 12 2011
a(32) and beyond from Michael S. Branicky, May 07 2021

A139052 Array read by rows: row n lists the first two primes with n digits.

Original entry on oeis.org

2, 3, 11, 13, 101, 103, 1009, 1013, 10007, 10009, 100003, 100019, 1000003, 1000033, 10000019, 10000079, 100000007, 100000037, 1000000007, 1000000009, 10000000019, 10000000033, 100000000003, 100000000019, 1000000000039, 1000000000061
Offset: 1

Views

Author

Omar E. Pol, Apr 08 2008

Keywords

Crossrefs

Programs

  • Mathematica
    ftp[d_]:=Module[{np1=NextPrime[10^(d-1)]},{np1,NextPrime[np1]}]; Array[ ftp,15]//Flatten (* Harvey P. Dale, Mar 27 2021 *)

Extensions

More terms from Sean A. Irvine, Jun 02 2011

A356987 Primes whose decimal expansion is 1, zero or more 0's, then a single digit.

Original entry on oeis.org

11, 13, 17, 19, 101, 103, 107, 109, 1009, 10007, 10009, 100003, 1000003, 100000007, 1000000007, 1000000009, 100000000003, 100000000000000003, 1000000000000000003, 1000000000000000009, 10000000000000000000009, 1000000000000000000000007
Offset: 1

Views

Author

Marco RipĂ , Sep 08 2022

Keywords

Comments

The sequence is a subsequence of A139054.
All the terms of this sequence are of the form 10^k + m, where m belongs to the set {1, 3, 7, 9} and k is a nonnegative integer.
If a term is of the form 10^k+m and k is odd, then m > 1. - Chai Wah Wu, Oct 22 2022

Examples

			1000000007 is a term because it is a prime number whose decimal expansion is 1, 8 zeros, then the single digit 7.
		

Crossrefs

Programs

Showing 1-3 of 3 results.