A230765 - OEIS

%I #12 Dec 23 2024 14:53:43

%S 3,1,2,4,5,6,7,9,10,11,13,8,15,17,12,19,31,33,21,35,37,39,14,51,53,55,

%T 57,16,59,71,73,75,77,23,79,91,93,95,97,18,99,111,110,113,115,117,119,

%U 112,131,133,135,137,139,30,151,153,155,114,157

%N Length of chunks of odd digits, delimited by an even digit, in the concatenation of all terms; smallest such sequence without duplicate terms.

%H E. Angelini, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2013-October/011815.html">Cut the sequence after it's odd/even digits</a>, SeqFan List, Oct 29 2013

%o (PARI) A230765_vec(n, a=[], s=[],u=0)={my(check(a, s)=my(L=0, j=1); !for(i=1, #s, ( i>L+a[j] || (( i==L+a[j] )== bittest(s[i],0))) && return; bittest(s[i],0) && next; L=i; j++)); check(a, s)||return; n-- || return(a); my(t); for(k=1, 9e9, bittest(u,k)&&next; (t=A230765_vec(n, concat(a, k), concat(s, digits(k)), u+2^k))&& return(t))}

%Y See A230764 for the "even" version.

%K nonn,base

%O 1,1

%A _Eric Angelini_ and _M. F. Hasler_, Oct 29 2013