Numbers k such that string 8,7 occurs in the base 10 representation of k but not of k+1.

Terms

a(0) =87a(1) =187a(2) =287a(3) =387a(4) =487a(5) =587a(6) =687a(7) =787a(8) =879a(9) =887a(10) =987a(11) =1087a(12) =1187a(13) =1287a(14) =1387a(15) =1487a(16) =1587a(17) =1687a(18) =1787a(19) =1879a(20) =1887a(21) =1987a(22) =2087a(23) =2187a(24) =2287a(25) =2387a(26) =2487a(27) =2587a(28) =2687a(29) =2787