A136307 a(n)=n*(10^K) + a(n-1); a(0)=1; K=floor(log_10 a(n-1))+1.

1, 11, 211, 3211, 43211, 543211, 6543211, 76543211, 876543211, 9876543211, 109876543211, 11109876543211, 1211109876543211, 131211109876543211, 14131211109876543211, 1514131211109876543211, 161514131211109876543211, 17161514131211109876543211, 1817161514131211109876543211

Offset

0,2

Links

Table of n, a(n) for n=0..18.

Maple

A136307 := proc(n)
    option remember;
    local k ;
    if n = 0 then
        1;
    else
        if procname(n-1) < 1 then
            k := 0;
        else
            k := 1+floor(log[10](procname(n-1))) ;
        end if ;
        procname(n-1)+n*10^k  ;
    end if;
end proc:
seq(A136307(n), n=0..10) ; # R. J. Mathar, Jun 20 2021

Mathematica

nxt[{n_, a_}]:={n+1, (n+1) 10^(Floor[Log[10, a]]+1)+a}; NestList[nxt, {0, 1}, 20][[All, 2]] (* Harvey P. Dale, Dec 07 2020 *)

Prog

(PARI) a(n) = if (n==0, 1, my(x=a(n-1), K=log(x)\log(10)+1); n*(10^K) + x); \\ Michel Marcus, Mar 16 2022

Crossrefs

Sequence in context: A069628 A069613 A075858 * A249604 A038399 A053547

Adjacent sequences: A136304 A136305 A136306 * A136308 A136309 A136310

Keyword

easy,nonn

Author

Ctibor O. Zizka, Mar 22 2008

Extensions

Offset corrected by R. J. Mathar, Jun 20 2021

More terms from Michel Marcus, Mar 16 2022

Status

approved