A045252 Numbers whose base-5 representation contains exactly one 1 and one 4.

9, 21, 29, 39, 44, 45, 47, 48, 59, 71, 84, 96, 101, 105, 107, 108, 111, 116, 129, 139, 144, 145, 147, 148, 179, 189, 194, 195, 197, 198, 204, 214, 219, 220, 222, 223, 225, 227, 228, 235, 237, 238, 240, 242, 243, 259, 271, 279, 289

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

d:= 4: # for all terms with up to d base-5 digits.
Res:= NULL;
for m from 0 to 3^(d-2)-1 do
     L:= subs(1=3, convert(3^(d-2)+m, base, 3));
     for i from 0 to d-2 do
       for j from i+1 to d-1 do
         xpos:= subs(i=NULL, j=NULL, [$0..d-1]);
         x:= add(L[i]*5^xpos[i], i=1..d-2);
         Res:= Res, x + 5^i+4*5^j, x+4*5^i+5^j
od od od:
sort([Res]); # Robert Israel, Jan 19 2020

Mathematica

Select[Range[300], DigitCount[#, 5, 1]==DigitCount[#, 5, 4]==1&] (* Harvey P. Dale, May 04 2021 *)

Prog

(Magma) [k:k in [1..300]| Multiplicity(Intseq(k, 5), 1) eq 1 and Multiplicity(Intseq(k, 5), 4) eq 1]; // Marius A. Burtea, Jan 20 2020

Crossrefs

Cf. A007091.

Sequence in context: A339728 A267216 A039289 * A139538 A173460 A110701

Adjacent sequences: A045249 A045250 A045251 * A045253 A045254 A045255

Keyword

nonn,base

Author

Clark Kimberling

Status

approved