login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

a(1) = 1, a(2) = 1, a(3) = a(1) + concatenation a(1), a(2). In general a(n) = a(1) + a(1)a(2)+ a(1)a(2)a(3) + ... + a(1)a(2)...a(n-1), where a(1)a(2)...a(r) is the concatenation of first r terms.
1

%I #6 Dec 05 2013 19:56:45

%S 1,1,12,1124,11122248,1112112422244496,

%T 11121124111222482224224844488992,

%U 1112112411122248111211242224449622242248222444964448449688977984

%N a(1) = 1, a(2) = 1, a(3) = a(1) + concatenation a(1), a(2). In general a(n) = a(1) + a(1)a(2)+ a(1)a(2)a(3) + ... + a(1)a(2)...a(n-1), where a(1)a(2)...a(r) is the concatenation of first r terms.

%F a(n) = concat(a(1), ..., a(n-1)) + a(n-1). - _Charles R Greathouse IV_, Mar 30 2004

%e a(3) = 1+11 = 12.

%Y Cf. A091781.

%K base,nonn

%O 1,3

%A _Amarnath Murthy_, Feb 17 2004

%E More terms from _Charles R Greathouse IV_, Mar 30 2004