OFFSET
1,1
COMMENTS
For any positive integer n, if a number of the form m^2+1 is divisible by 5^n, then m mod 5^n must take one of two values--one even, the other odd. This sequence gives the even residue. (The odd residues are in A259266.)
EXAMPLE
If m^2+1 is divisible by 5, then m mod 5 is either 2 or 3; the even value is 2, so a(1)=2.
If m^2+1 is divisible by 5^2, then m mod 5^2 is either 7 or 18; the even value is 18, so a(2)=18.
If m^2+1 is divisible by 5^3, then m mod 5^3 is either 57 or 68; the even value is 68, so a(3)=68.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jon E. Schoenfield, Jun 15 2015
EXTENSIONS
More terms and additional comments from Jon E. Schoenfield, Jun 23 2015
STATUS
approved