# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a058935 Showing 1-1 of 1 %I A058935 #39 Apr 19 2023 12:59:33 %S A058935 0,1,110,11011,11011100,11011100101,11011100101110,11011100101110111, %T A058935 110111001011101111000,1101110010111011110001001, %U A058935 11011100101110111100010011010,110111001011101111000100110101011,1101110010111011110001001101010111100 %N A058935 Concatenation of first n binary numbers. %C A058935 If the terms are read as decimal numbers, which of them are primes? For example, a(5) = 11011100101 = 1193*9229757 is not a prime. - _N. J. A. Sloane_, Feb 17 2023 %C A058935 Answer: a(231) is the first prime term when read as a decimal number; a(15) is the first when read as a binary number. - _Michael S. Branicky_, Feb 17 2023 %H A058935 Michael S. Branicky, Table of n, a(n) for n = 0..155 %H A058935 Eric Weisstein's World of Mathematics, Binary Champernowne Constant %H A058935 Eric Weisstein's World of Mathematics, Smarandache Number %H A058935 Index entries for sequences related to Most Wanted Primes video %F A058935 a(n) = a(n-1)*10^A029837(n) + A007088(n). %t A058935 FromDigits /@ Flatten /@ Rest[FoldList[Append, {}, IntegerDigits[Range[10], 2]]] (* _Eric W. Weisstein_, Nov 04 2015 *) %o A058935 (Python) %o A058935 from itertools import count, islice %o A058935 def agen(s=""): yield from (int(s:=s+bin(n)[2:]) for n in count(0)) %o A058935 print(list(islice(agen(), 13))) # _Michael S. Branicky_, Feb 17 2023 %o A058935 (Python) %o A058935 from functools import reduce %o A058935 def A058935(n): return int(bin(reduce(lambda i,j:(i<