A244808 - OEIS

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A244808

The hexagonal spiral of Champernowne, read along the 60-degree ray.

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

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OFFSET

1,3

LINKS

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

FORMULA

(12n^2-27n+16)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 - 27n + 16 (* see formula section of A244807 *); Array[ almostNatural[ f@#, 10] &, 105]

CROSSREFS

Cf. A007376, A244802, A244807, A244809, A244810, A244811, A244812, A244813, A244814, A244815, A244816, A244817, A244818.

Sequence in context: A351335 A021862 A199375 * A351055 A359284 A157295

Adjacent sequences: A244805 A244806 A244807 * A244809 A244810 A244811

KEYWORD

nonn,easy

AUTHOR

Robert G. Wilson v, Jul 06 2014

STATUS

approved