A032857 - OEIS

%I #11 Feb 12 2021 22:05:46

%S 1,2,3,4,5,6,7,8,9,11,12,13,14,15,16,17,18,19,22,23,24,25,26,27,28,29,

%T 33,34,35,36,37,38,39,44,45,46,47,48,49,55,56,57,58,59,66,67,68,69,77,

%U 78,79,88,89,99,110,111,120,121,122,130,131

%N Numbers whose base-10 representation Sum_{i=0..m} d(i)*10^i, d(m) > 0, has d(m) <= d(m-1) >= d(m-2) <= ...

%C The second digit must be greater than or equal to the first, the third digit must be less than or equal to the second, etc. - _M. F. Hasler_, Mar 08 2014

%o (PARI) is_A032857(n)=!for(i=2,#n=digits(n),(n[i]-n[i-1])*(-1)^i<0&&return) \\ _M. F. Hasler_, Mar 08 2014

%K nonn,base

%O 1,2

%A _Clark Kimberling_