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”).

Define the first two terms to be 1 and 7. All the other terms are obtained by concatenating the two previous terms.
0

%I #3 Mar 30 2012 18:49:39

%S 1,7,17,717,17717,71717717,1771771717717,717177171771771717717,

%T 1771771717717717177171771771717717,

%U 7171771717717717177171771771717717717177171771771717717

%N Define the first two terms to be 1 and 7. All the other terms are obtained by concatenating the two previous terms.

%C a(n) has Fibonacci(n) digits and the sum of all digits is given by Fibonacci(n-2)+7*Fibonacci(n-1) for all n>4. - _Stefan Steinerberger_, Jan 21 2006

%e The third term is 17 and it is obtained by concatenating the two previous terms 1 and 7.

%Y Cf. A008352, A113526.

%Y Cf. A000045 - the Fibonacci numbers.

%K nonn,base

%O 0,2

%A _Parthasarathy Nambi_, Jan 18 2006

%E More terms from _Stefan Steinerberger_, Jan 21 2006