A104613 - OEIS

%I #5 Apr 23 2012 21:43:49

%S 1,3,6,0,1,1,0,4,3,3,1,7,5,6,1,0,1,1,1,1,1,3,1,1,6,1,1,0,2,2,3,2,2,7,

%T 2,3,2,3,3,6,3,4,2,4,4,7,5,5,3,5,5,0,6,6,6,6,7,3,7,7,1,8,8,8,1,3,0,0,

%U 8,1,6,6,1,0,2,2,7,1,4,6,1,0,4,4,7,1,0,4,1,1,6,6,0,1,3,0,1,4,8,0,3,2,4,3,2

%N Write the natural numbers in base 9 in a triangle with k digits in the k-th row, as shown below. Sequence gives the leading diagonal.

%C 1

%C 23

%C 456

%C 7810

%C 11121

%C 314151...

%t t = Flatten[ IntegerDigits[ Range[1800], 9]]; t[[Table[n(n + 1)/2, {n, 105}]]]

%o (PARI) { pln=0; Trn = 1; Trd=1;

%o for(ixp=1, 1625, casi = ixp; cvst=0;

%o while(casi != 0, cvd = casi%9;

%o cvst=10*cvst + cvd + 1; casi = (casi - cvd) / 9 );

%o while(cvst !=0, ptch = cvst%10; pln++;

%o if(Trn==pln, print1(ptch-1, ", "); Trd++; Trn=Trn+Trd);

%o cvst = (cvst - ptch) / 10 ) ) } \\\ _Douglas Latimer_, Apr 23 2012

%Y Cf. A104606, A104607, A104608, A104609, A104610, A104611, A104612, A091425, A104614, A104615, A104616, A104617, A104618, A104619, A104620.

%K base,nonn

%O 1,2

%A _Robert G. Wilson v_, Mar 16 2005