A104613 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.

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, 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, 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

Offset: 1

Author

Robert G. Wilson v, Mar 16 2005

Keywords

• base
• nonn

Comments

1

23

456

7810

11121

314151...

Crossrefs

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

Programs

Mathematica

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

PARI

{ pln=0; Trn = 1; Trd=1;
for(ixp=1, 1625, casi = ixp; cvst=0;
while(casi != 0, cvd = casi%9;
cvst=10*cvst + cvd + 1; casi = (casi - cvd) / 9 );
while(cvst !=0, ptch = cvst%10; pln++;
if(Trn==pln, print1(ptch-1, ", "); Trd++; Trn=Trn+Trd);
cvst = (cvst - ptch) / 10 ) ) } \\\ Douglas Latimer, Apr 23 2012