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A037805
Number of i such that d(i) < d(i-1), where Sum_{i=0..m} d(i)*7^i is the base-7 representation of n.
2
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 2
OFFSET
1,66
MAPLE
A037805 := proc(n)
a := 0 ;
dgs := convert(n, base, 7);
for i from 2 to nops(dgs) do
if op(i, dgs)<op(i-1, dgs) then
a := a+1 ;
end if;
end do:
a ;
end proc: # R. J. Mathar, Oct 16 2015
PROG
(PARI) a(n) = {my(d = Vecrev(digits(n, 7))); my(dd = vector(#d-1, k, d[k+1] - d[k])); #select(x->(x<0), dd); } \\ Michel Marcus, Oct 16 2015
CROSSREFS
Cf. A037822.
Sequence in context: A145884 A030368 A258383 * A327144 A327051 A367912
KEYWORD
nonn,base
EXTENSIONS
Sign in name corrected by R. J. Mathar, Oct 16 2015
STATUS
approved