A261167 - OEIS

%I #9 Dec 23 2024 14:53:44

%S 1,7,0,2,3,4,5,6,8,77,9,17,10,27,11,12,70,13,14,71,15,16,37,18,19,20,

%T 21,72,22,23,24,25,26,28,29,30,31,32,33,34,35,36,38,39,40,41,42,43,44,

%U 45,46,48,49,50,51,52,53,54,55,56,58,59,60,61,62,63,73,64,65,66,68,74,69

%N List run lengths of digits different from '7', when all terms are concatenated. Lexicographically first such sequence of nonnegative numbers with no repeated terms.

%C See A261161-A261163 for comments and examples.

%H E. Angelini, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2015-August/015191.html">To reach the next "1"</a>, SeqFan list, August 10, 2015.

%o (PARI) A261167(n=99,d=7,a=1,p=0,u=[-1],r=u)={for(n=2,n, print1(a","); p+=#digits(a)+!a; r=concat(r,r[#r]+a+1); while(#r>1&&r[1]<p,r=r[2..-1]); u=setunion(u,[a]);while(#u>1&&u[2]==u[1]+1,u=u[2..-1]); for(k=u[1]+1,9e9,setsearch(u,k)&&next; if(r[1] >= p+#dk=if(k,digits(k),[0]), setsearch(Set(dk),d)&&next, for(i=1,#dk,(dk[i]==d)==!setsearch(r,p+i-1)&&next(2))); a=k;next(2));error);a}

%Y Cf. A261160 - A261166, A261168, A261169.

%K nonn,base

%O 1,2

%A _Eric Angelini_ and _M. F. Hasler_, Aug 10 2015