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A222257

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

3

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

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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