Voozh

A076063

Group the natural numbers so that the n-th group contains n numbers whose sum is a multiple of the n-th composite number.

4, 1, 5, 2, 3, 11, 6, 7, 8, 15, 9, 10, 12, 13, 16, 14, 17, 18, 19, 20, 32, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 50, 36, 37, 38, 39, 40, 41, 42, 43, 52, 44, 45, 46, 47, 48, 49, 51, 53, 54, 67, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 68, 69, 70, 71, 72

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OFFSET

1,1

COMMENTS

The first n-1 numbers of row n are selected by simply choosing the smallest n-1 numbers which have not yet been used. The remaining number is then chosen to be the smallest possible unused number such that the sum of the n numbers is a multiple of composite(n) = A002808(n). - Sean A. Irvine, Mar 16 2025

LINKS

Sean A. Irvine, Table of n, a(n) for n = 1..1540 (rows 1..20 flattened)

EXAMPLE

1,5;

2,3,11;

6,7,8,15;

9,10,12,13,16;

14,17,18,19,20,32; ...

CROSSREFS

Cf. A002808, A076064, A076065, A076066, A076067.

Sequence in context: A269593 A194512 A131230 * A035590 A168230 A080414

Adjacent sequences: A076060 A076061 A076062 * A076064 A076065 A076066