A076105 - OEIS

A076105

a(1)=1 (first row) and then the n-th row of this triangle contains the least set of n unused natural numbers whose sum is a multiple of the sum of the previous row.

1, 2, 3, 4, 5, 6, 7, 8, 9, 21, 10, 11, 12, 13, 44, 14, 15, 16, 17, 18, 100, 19, 20, 22, 23, 24, 25, 47, 26, 27, 28, 29, 30, 31, 32, 157, 33, 34, 35, 36, 37, 38, 39, 40, 68, 41, 42, 43, 45, 46, 48, 49, 50, 51, 305, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 155, 62, 63, 64, 65, 66, 67

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OFFSET

1,2

COMMENTS

The first (n-1) terms of the n-th row contain n-1 smallest natural numbers which have not occurred earlier and the last term is chosen to satisfy the requirement. Permutation A094280 is defined similarly, but the sum of the next row must be greater than that of the current row.

LINKS

Table of n, a(n) for n=1..72.

Index entries for sequences that are permutations of the natural numbers

EXAMPLE

2, 3;

4, 5, 6;

7, 8, 9, 21;

10, 11, 12, 13, 44;

14, 15, 16, 17, 18, 100;

CROSSREFS

Inverse: A122154. Cf. A076101, A076102, A076103, A076104.

Sequence in context: A079170 A330927 A319387 * A094280 A082323 A069571