OFFSET
0,4
COMMENTS
Looking at the Fibonacci numbers modulo 10 (A003893), we see their parity and what their least significant digits are in base 10. But it doesn't tell us whether the even Fibonacci numbers are further divisible by 2, nor does it tell us the congruence modulo 4 of the odd Fibonacci numbers.
Modulo 20, the Fibonacci numbers have a period of 60. Aside from 2, 3, 5, Fibonacci primes have a least significant digit of 9, D or J in vigesimal.
LINKS
Index entries for linear recurrences with constant coefficients, signature (1, -1, 1, -1, 1, 0, 0, 0, 0, 0, 0, -1, 1, -1, 1, -1, 1, 0, 0, 0, 0, 0, 0, -1, 1, -1, 1, -1, 1, 0, 0, 0, 0, 0, 0, -1, 1, -1, 1, -1, 1, 0, 0, 0, 0, 0, 0, -1, 1, -1, 1, -1, 1).
MATHEMATICA
Mod[Fibonacci[Range[0, 79]], 20]
PROG
(PARI) a(n)=fibonacci(n%60)%20 \\ Charles R Greathouse IV, Jun 23 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alonso del Arte, May 26 2017
STATUS
approved