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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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This is a self-inverse permutation of the positive integers. For fixed n, U(n,k) as defined above is a permution of 1..n. - Franklin T. Adams-Watters, Jul 25 2006

LINKS

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

FORMULA

T(n,k) = n(n-1)/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. Adams-Watters, 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. Adams-Watters, Jul 25 2006

STATUS

approved

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Last modified September 23 20:42 EDT 2021. Contains 347617 sequences. (Running on oeis4.)