A105472 - OEIS

%I #22 Aug 22 2020 11:46:36

%S 0,0,0,0,0,0,0,1,2,3,5,8,4,3,7,1,8,9,8,8,6,4,1,5,6,2,9,1,1,2,4,6,0,7,

%T 8,6,5,1,6,8,5,4,9,3,3,7,0,7,7,4,2,7,9,7,7,4,1,6,7,4,2,6,8,4,2,6,8,5,

%U 4,9,3,2,6,9,5,5,0,5,6,2,8,0,9,9,8,8,7,5,3,8,2,0,2,3,6,0,7,7,4,2,7,0,7,7,5

%N Next-to-last digit of n-th Fibonacci number in decimal representation, a(n) = 0 for n <= 6.

%C a(n) = floor(A105471(n)/10) = floor(A000045(n)/10) mod 10;

%C A105471(n) = a(n)*10 + A003893(n);

%C the sequence is periodic with period 300; all blocks of 300 successive terms contain 160 even and 140 odd numbers.

%H Alois P. Heinz, <a href="/A105472/b105472.txt">Table of n, a(n) for n = 0..10000</a> (first 601 terms from Alex Ermolaev)

%t Array[Mod[Floor[Fibonacci[#]/10], 10] &, 105, 0] (* _Michael De Vlieger_, Jan 04 2018 *)

%t Join[{0,0,0,0,0,0,0},Table[IntegerDigits[Fibonacci[n]][[-2]],{n,7,120}]] (* _Harvey P. Dale_, Aug 22 2020 *)

%o (PARI) a(n) = (fibonacci(n) % 100)\10; \\ _Michel Marcus_, Jan 05 2018

%Y Cf. A000045, A003893, A105471.

%K nonn,base

%O 0,9

%A _Reinhard Zumkeller_, Apr 09 2005