

A297254


Numbers whose base4 digits have greater upvariation than downvariation; see Comments.


4



6, 7, 11, 18, 19, 22, 23, 26, 27, 30, 31, 35, 39, 43, 47, 66, 67, 70, 71, 74, 75, 78, 79, 82, 83, 86, 87, 90, 91, 94, 95, 98, 99, 102, 103, 106, 107, 110, 111, 114, 115, 118, 119, 122, 123, 126, 127, 131, 135, 139, 143, 147, 151, 155, 159, 163, 167, 171, 175
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OFFSET

1,1


COMMENTS

Suppose that n has baseb digits b(m), b(m1), ..., b(0). The baseb downvariation of n is the sum DV(n,b) of all d(i)d(i1) for which d(i) > d(i1); the baseb upvariation of n is the sum UV(n,b) of all d(k1)d(k) for which d(k) < d(k1). The total baseb variation of n is the sum TV(n,b) = DV(n,b) + UV(n,b). See the guide at A297330.


LINKS

Clark Kimberling, Table of n, a(n) for n = 1..10000


EXAMPLE

175 in base4: 2,2,3,3, having DV = 0, UV = 1, so that 175 is in the sequence.


MATHEMATICA

g[n_, b_] := Map[Total, GatherBy[Differences[IntegerDigits[n, b]], Sign]];
x[n_, b_] := Select[g[n, b], # < 0 &]; y[n_, b_] := Select[g[n, b], # > 0 &];
b = 4; z = 2000; p = Table[x[n, b], {n, 1, z}]; q = Table[y[n, b], {n, 1, z}];
w = Sign[Flatten[p /. {} > {0}] + Flatten[q /. {} > {0}]];
Take[Flatten[Position[w, 1]], 120] (* A297252 *)
Take[Flatten[Position[w, 0]], 120] (* A297253 *)
Take[Flatten[Position[w, 1]], 120] (* A297254 *)


CROSSREFS

Cf. A297330, A297252, A297253.
Sequence in context: A182156 A166496 A267413 * A296695 A228948 A297128
Adjacent sequences: A297251 A297252 A297253 * A297255 A297256 A297257


KEYWORD

nonn,base,easy


AUTHOR

Clark Kimberling, Jan 15 2018


STATUS

approved



