A244816 The hexagonal spiral of Champernowne, read along the South (or 180-degree) ray.

1, 1, 4, 6, 7, 4, 1, 4, 0, 3, 3, 3, 6, 4, 4, 9, 5, 1, 2, 8, 2, 1, 7, 9, 5, 2, 3, 9, 4, 2, 0, 9, 9, 3, 7, 9, 0, 4, 6, 8, 7, 5, 6, 7, 0, 6, 6, 6, 9, 7, 8, 4, 4, 8, 0, 2, 5, 6, 3, 3, 0, 1, 9, 0, 1, 2, 4, 2, 7, 1, 4, 9, 5, 4, 3, 5, 6, 8, 1, 7, 7, 4, 1, 8, 4, 9, 5, 4, 5, 2, 1, 8, 7, 2, 2, 3, 3, 0, 9, 4, 6, 0, 3, 6, 8

Offset

1,3

Links

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

Formula

(12n^2 - 19n + 8)th almost natural number (A033307), Also see formula section of A056105.

Example

see A244807 example section for its diagram.

Mathematica

almostNatural[n_, b_] := Block[{m = 0, d = n, i = 1, l, p}, While[m <= d, l = m; m = (b - 1) i*b^(i - 1) + l; i++]; i--; p = Mod[d - l, i]; q = Floor[(d - l)/i] + b^(i - 1); If[p != 0, IntegerDigits[q, b][[p]], Mod[q - 1, b]]]; f[n_] := 12n^2 - 19n + 8 (* see formula section of A244807 *); Array[ almostNatural[ f@#, 10] &, 105]

Crossrefs

Cf. A007376, A244806, A244807, A244808, A244809, A244810, A244811, A244812, A244813, A244814, A244815, A244817, A244818.

Sequence in context: A344983 A237515 A200939 * A197585 A019605 A201564

Adjacent sequences: A244813 A244814 A244815 * A244817 A244818 A244819

Keyword

nonn,easy

Author

Robert G. Wilson v, Jul 06 2014

Status

approved