|
%I #4 Jan 15 2018 21:08:21
%S 6,12,13,18,19,20,24,25,26,27,30,31,32,33,34,36,42,48,54,60,66,72,73,
%T 78,79,84,85,90,91,96,97,102,103,108,109,110,114,115,116,120,121,122,
%U 126,127,128,132,133,134,138,139,140,144,145,146,147,150,151,152
%N Numbers whose base-6 digits have greater down-variation than up-variation; see Comments.
%C Suppose that n has base-b digits b(m), b(m-1), ..., b(0). The base-b down-variation of n is the sum DV(n,b) of all d(i)-d(i-1) for which d(i) > d(i-1); the base-b up-variation of n is the sum UV(n,b) of all d(k-1)-d(k) for which d(k) < d(k-1). The total base-b variation of n is the sum TV(n,b) = DV(n,b) + UV(n,b). See the guide at A297330.
%H Clark Kimberling, <a href="/A297258/b297258.txt">Table of n, a(n) for n = 1..10000</a>
%e 152 in base-6: 4,1,2, having DV = 3, UV = 1, so that 152 is in the sequence.
%t g[n_, b_] := Map[Total, GatherBy[Differences[IntegerDigits[n, b]], Sign]];
%t x[n_, b_] := Select[g[n, b], # < 0 &]; y[n_, b_] := Select[g[n, b], # > 0 &];
%t b = 6; z = 2000; p = Table[x[n, b], {n, 1, z}]; q = Table[y[n, b], {n, 1, z}];
%t w = Sign[Flatten[p /. {} -> {0}] + Flatten[q /. {} -> {0}]];
%t Take[Flatten[Position[w, -1]], 120] (* A297258 *)
%t Take[Flatten[Position[w, 0]], 120] (* A297259 *)
%t Take[Flatten[Position[w, 1]], 120] (* A297260 *)
%Y Cf. A297330, A297259, A297260.
%K nonn,base,easy
%O 1,1
%A _Clark Kimberling_, Jan 15 2018
|
