A076077 Group the natural numbers so that the n-th group contains n numbers, the k-th number in a group is a multiple of k and the sum of the group is prime: (2), (1, 4), (3, 8, 6), (5, 10, 12, 16), (7, 14, 9, 24, 25), ...

2, 1, 4, 3, 8, 6, 5, 10, 12, 16, 7, 14, 9, 24, 25, 11, 18, 15, 20, 45, 30, 13, 22, 21, 28, 35, 36, 42, 17, 26, 27, 32, 40, 48, 49, 72, 19, 34, 33, 44, 50, 54, 56, 80, 63, 23, 38, 39, 52, 55, 60, 70, 64, 90, 110, 29, 46, 51, 68, 65, 66, 77, 88, 81, 120, 132, 31, 58, 57, 76, 75

Offset

1,1

Comments

For 1 <= k <= n-2, T(n, k) is the smallest multiple of k not already used. T(n, n-1) must be chosen so that T(n, 1)+...+T(n, n-1) is relatively prime to n. - David Wasserman, Mar 24 2005

Links

Table of n, a(n) for n=1..71.

Example

2; 1,4; 3,8,6; 5,10,12,16; 7,14,9,24,25; ...

Crossrefs

Cf. A076074, A076075, A076076.

Sequence in context: A193174 A126084 A294022 * A152194 A268630 A087787

Adjacent sequences: A076074 A076075 A076076 * A076078 A076079 A076080

Keyword

nonn

Author

Amarnath Murthy, Oct 05 2002

Extensions

More terms from David Wasserman, Mar 24 2005

Status

approved