A104611 Write the natural numbers in base 7 in a triangle with k digits in the k-th row, as shown below. Sequence gives the leading diagonal.

1, 3, 6, 1, 1, 2, 3, 0, 3, 4, 1, 0, 1, 4, 2, 1, 6, 5, 1, 4, 4, 2, 5, 6, 2, 2, 4, 3, 2, 5, 3, 5, 2, 4, 4, 2, 5, 6, 5, 5, 4, 4, 6, 0, 2, 1, 3, 1, 1, 3, 1, 2, 2, 1, 1, 1, 1, 5, 4, 4, 4, 1, 1, 3, 1, 2, 6, 0, 2, 2, 3, 0, 2, 1, 2, 2, 2, 2, 0, 6, 2, 2, 5, 6, 4, 3, 6, 0, 3, 6, 2, 2, 2, 3, 0, 3, 3, 5, 6, 6, 2, 4, 3, 1, 4

Offset

1,2

Comments

1

23

456

1011

12131

415162...

Links

Table of n, a(n) for n=1..105.

Mathematica

t = Flatten[ IntegerDigits[ Range[1500], 7]]; t[[Table[n(n + 1)/2, {n, 105}]]]
Module[{d = Flatten[Table[IntegerDigits[n, 7], {n, 2000}]]}, TakeList[ d, Range[(Sqrt[8*Length[d] + 1] - 1)/2]]][[All, -1]] (* Requires Mathematica version 11 or later *) (* Harvey P. Dale, Jul 09 2020 *)

Crossrefs

Cf. A104606, A104607, A104608, A104609, A104610, A104612, A104613, A091425, A104614, A104615, A104616, A104617, A104618, A104619, A104620.

Sequence in context: A177022 A325634 A008953 * A076790 A095693 A368569

Adjacent sequences: A104608 A104609 A104610 * A104612 A104613 A104614

Keyword

base,nonn

Author

Robert G. Wilson v, Mar 16 2005

Status

approved