A037816 Number of i such that d(i) <= d(i-1), where Sum_{i=0..m} d(i)*9^i is the base-9 representation of n.

0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1

Offset

1,1

Comments

Equivalently, number of nonnegative terms in the first differences of the digits of the base-9 representation of n. - Paolo Xausa, Nov 19 2025

Links

Chris R. Rehmann, Table of n, a(n) for n = 1..10000

Maple

A037816 := proc(n)
    a := 0 ;
    dgs := convert(n, base, 9);
    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

Mathematica

A037816[n_] := Count[Differences[IntegerDigits[n, 9]], _?NonNegative];
Array[A037816, 100] (* Paolo Xausa, Nov 19 2025 *)

Prog

(MATLAB) n = 1:10000; a = arrayfun(@(m) sum(diff(dec2base(m, 9)-'0')>=0), n); % Chris R. Rehmann, Nov 18 2025

Crossrefs

Cf. A007095, A037832.

Cf. A037809, A037810, A037811, A037812, A037813, A037814, A037815, A037817.

Sequence in context: A037913 A037833 A369640 * A353639 A353569 A353477

Adjacent sequences: A037813 A037814 A037815 * A037817 A037818 A037819

Keyword

nonn,base,easy

Author

Clark Kimberling

Extensions

Sign in Name corrected by R. J. Mathar, Oct 16 2015

Status

approved