OFFSET
1,1
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000
EXAMPLE
27 is in the sequence as 27_10 = 123_4 which has 23 juxtaposed in its base-4 representationand 28_10 = 130_4 does not have 23 juxtaposed in its base-4 representation. - David A. Corneth, Aug 28 2023
MATHEMATICA
SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 4], {2, 3}]>0 || SequenceCount[ IntegerDigits[ n, 4], {3, 2}]>0, 1, 0], {n, 500}], {1, 0}][[;; , 1]] (* Harvey P. Dale, Aug 28 2023 *)
PROG
(PARI) is(n) = {has23juxtaposed(n) && !has23juxtaposed(n+1)}
has23juxtaposed(n) = {my(d = digits(n, 4)); for(i = 1, #d-1, if(d[i] == 2 && d[i+1] == 3, return(1)); if(d[i] == 3 && d[i+1] == 2, return(1))); 0} \\ David A. Corneth, Aug 28 2023
CROSSREFS
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
More terms from David A. Corneth, Aug 28 2023
STATUS
approved