login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

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.
1
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
0,1
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.
LINKS
EXAMPLE
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
PROG
(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
CROSSREFS
Sequence in context: A185682 A217752 A335646 * A287468 A110417 A240560
KEYWORD
nonn,tabl,base
AUTHOR
Felix Fröhlich, Aug 10 2015
EXTENSIONS
More terms from Alois P. Heinz, Aug 17 2015
STATUS
approved