A222257 Lexicographically earliest injective sequence of positive integers such that the sum of 6 consecutive terms is always divisible by 6.

1, 2, 3, 4, 5, 9, 7, 8, 15, 10, 11, 21, 13, 14, 27, 16, 17, 33, 19, 20, 39, 22, 23, 45, 25, 26, 51, 28, 29, 57, 31, 32, 63, 34, 35, 69, 37, 38, 75, 40, 41, 81, 43, 44, 87, 46, 47, 93, 49, 50, 99, 52, 53, 105, 55, 56, 111, 58, 59, 117, 61, 62, 123, 64, 65, 129, 67, 68, 135, 70, 71, 141, 73

Offset

0,2

Links

Table of n, a(n) for n=0..72.

E. Angelini, k-chunks sum and division by k, post to the SeqFan list, Mar 22 2013

Formula

a(n) = 2 a(n-3) - a(n-6).

G.f. (1 + 2*x + 3*x^2 + 2*x^3 + x^4 + 3*x^5)/((1 - x)*(1 + x + x^2))^2.

Crossrefs

Cf. A222256, A222258 - A222261.

Sequence in context: A323136 A273285 A068795 * A327456 A238535 A327415

Adjacent sequences: A222254 A222255 A222256 * A222258 A222259 A222260

Keyword

nonn

Author

Eric Angelini and M. F. Hasler, Mar 23 2013

Status

approved