|
|
A225017
|
|
Odd part of digit sum of 5^n divided by maximal possible power of 5.
|
|
9
|
|
|
1, 1, 7, 1, 13, 11, 19, 23, 1, 13, 1, 19, 7, 23, 17, 11, 29, 7, 1, 59, 61, 31, 67, 37, 41, 77, 79, 89, 17, 83, 91, 13, 53, 89, 103, 23, 109, 13, 31, 67, 13, 137, 29, 149, 151, 29, 7, 1, 29, 79, 151, 19, 13, 119, 127, 167, 49, 43, 211, 191, 199, 97, 187, 17, 83
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
Does the sequence contain every prime greater than 5?
|
|
LINKS
|
|
|
FORMULA
|
|
|
MAPLE
|
a:= proc(n) local m, r; m, r:= 0, 5^n;
while r>0 do m:= m+irem(r, 10, 'r') od;
while irem(m, 2, 'r')=0 do m:=r od;
while irem(m, 5, 'r')=0 do m:=r od; m
end:
|
|
MATHEMATICA
|
Map[#/(2^IntegerExponent[#, 2] 5^IntegerExponent[#, 5])&[Total[ IntegerDigits[5^#]]]&, Range[0, 99]] (* Peter J. C. Moses, Apr 24 2013 *)
|
|
PROG
|
(PARI) a(n) = my(x = sumdigits(5^n)); x/5^valuation(x, 5) >> valuation(x, 2); \\ Michel Marcus, Dec 10 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|