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.

A261173 Table read by antidiagonals: T(n,k) = smallest prime p containing only digits 0 and 1 with n 0's and k 1's, or 0 if no such p exists.

Original entry on oeis.org

11, 0, 101, 0, 0, 0, 0, 10111, 0, 0, 0, 101111, 0, 0, 0, 0, 0, 0, 1011001, 0, 0, 0, 11110111, 0, 10011101, 10010101, 0, 0, 0, 101111111, 101101111, 0, 100100111, 101001001, 0, 0, 0, 0, 1010111111, 1001110111, 0, 1000011011, 1000001011, 0, 0
Offset: 0

Views

Author

Felix Fröhlich, Aug 10 2015

Keywords

Comments

T(n, k) = 0 if k is a term of A008585.
T(0, k) != 0 iff k is a term of A004023.
T(1, k) = A157709(k-2) for all k >= 4.
T(n, 2) != 0 iff A062397(n+1) is prime.
a(n) is in A168586 iff it is the smallest p in T with A007953(p) = k.

Examples

			Table T(n, k) starts
     k = 2        3        4        5
      -------------------------------------
n = 0 |  11       0        0        0
n = 1 |  101      0        10111    101111
n = 2 |  0        0        0        0
n = 3 |  0        0        1011001  10011101
		

Crossrefs

Programs

  • PARI
    a(n, k) = i=0; forprime(p=10^(n+k-1), (10^(n+k)-1)/9, if(vecmax(digits(p))==1 && sumdigits(p)==k, return(p); i++; break)); if(i==0, return(0))
    table(row, col) = for(x=0, row, for(y=2, col, print1(a(x, y), " ")); print(""))
    table(4, 5) \\ print 5 X 4 table

Extensions

More terms from Alois P. Heinz, Aug 17 2015