A136695 - OEIS (original) (raw)

1, 1, 2, 6, 3, 7, 2, 6, 6, 6, 4, 4, 6, 6, 4, 4, 3, 3, 6, 2, 5, 1, 6, 2, 6, 6, 4, 4, 6, 6, 4, 4, 6, 6, 4, 4, 2, 2, 4, 4, 4, 4, 1, 3, 4, 4, 3, 5, 6, 6, 4, 4, 2, 2, 4, 4, 4, 4, 3, 1, 4, 4, 5, 3, 3, 3, 6, 2, 1, 5, 6, 2, 2, 2, 4, 4, 2, 2, 4, 4, 5, 5, 2, 6, 3, 7, 2, 6, 2, 2, 4, 4, 2, 2, 4, 4, 6, 6, 4, 4

FORMULA

If A011371(n) == 1 (mod 3) then a(n) = 2*(A049606(n) mod 4).

If A011371(n) == 2 (mod 3) then a(n) = 4. (End)

EXAMPLE

6! = 720 decimal = 1320 octal, so a(6) = 2.

MAPLE

P:= 1: E:= 0: a[0]:= 1:

for n from 1 to 100 do

v:= padic:-ordp(n, 2);

P:= P*(n/2^v) mod 8;

E:= E + v;

if E mod 3 = 0 then a[n]:= P

elif E mod 3 = 1 then a[n]:= 2*(P mod 4)

else a[n]:= 4

fi

od:

MATHEMATICA

Table[IntegerDigits[FromDigits[Reverse[IntegerDigits[n!, 8]]]][[1]], {n, 0, 100}] (* Harvey P. Dale, Nov 29 2024 *)

CROSSREFS

Cf. A000142, A136690, A136691, A136692, A136693, A136694, A136696, A008904, A136697, A136698, A136699, A136700, A136701, A136702.