

A120913


Triangle read by rows where t(n,m) is the (ceiling(n/m))th integer from among those positive integers not occurring earlier in the sequence.


1



1, 3, 2, 6, 5, 4, 10, 8, 9, 7, 15, 13, 12, 14, 11, 21, 18, 17, 19, 20, 16, 28, 25, 24, 23, 26, 27, 22, 36, 32, 31, 30, 33, 34, 35, 29, 45, 41, 39, 40, 38, 42, 43, 44, 37, 55, 50, 49, 48, 47, 51, 52, 53, 54, 46, 66, 61, 59, 58, 60, 57, 62, 63, 64, 65, 56, 78, 72, 70, 69, 71, 68
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OFFSET

1,2


COMMENTS

This is a selfinverse permutation of the positive integers. For fixed n, U(n,k) as defined above is a permution of 1..n.  Franklin T. AdamsWatters, Jul 25 2006


LINKS

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


FORMULA

T(n,k) = n(n1)/2 + U(n,k), where U(n,k) = ceiling(n/k) if ceiling(n/ceiling(n/k)) = k, otherwise U(n,k) = k.  Franklin T. AdamsWatters, Jul 25 2006


CROSSREFS

Cf. A120911.
Sequence in context: A194839 A195071 A195081 * A194922 A195080 A194858
Adjacent sequences: A120910 A120911 A120912 * A120914 A120915 A120916


KEYWORD

easy,nonn,tabl


AUTHOR

Leroy Quet, Jul 15 2006


EXTENSIONS

More terms from Franklin T. AdamsWatters, Jul 25 2006


STATUS

approved



