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A115409 Inverse integer permutation of A115408. 4
1, 5, 4, 7, 6, 2, 17, 16, 12, 10, 20, 19, 15, 13, 3, 43, 42, 38, 36, 26, 23, 51, 50, 46, 44, 34, 31, 8, 105, 104, 100, 98, 88, 85, 62, 54, 114, 113, 109, 107, 97, 94, 71, 63, 9 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Seen as a triangle read by rows T(n,k) = a(n*(n-1)/2+k) = A024431(n)-A024431(k-1), 1<=k<=n.

T(n,1) = A024431(n)-1; T(n,n) = A247414(n-1). - Reinhard Zumkeller, Sep 16 2014

LINKS

Reinhard Zumkeller, >Rows n = 1..125 of triangle, flattened

Index entries for sequences that are permutations of the natural numbers

PROG

(Haskell)

import Data.List (inits)

a115409 n k = a115409_tabl !! (n-1) !! (k-1)

a115409_row n = a115409_tabl !! (n-1)

a115409_tabl = map f $ drop 2 $ inits a024431_list where

   f xs = reverse $ map (z -) zs where (z:zs) = reverse xs

a115409_list = concat a115409_tabl

-- Reinhard Zumkeller, Sep 16 2014

CROSSREFS

Cf. A024431, A247414.

Sequence in context: A195428 A254373 A004446 * A010775 A010485 A194362

Adjacent sequences:  A115406 A115407 A115408 * A115410 A115411 A115412

KEYWORD

nonn,tabl,look

AUTHOR

Reinhard Zumkeller, Jan 22 2006

STATUS

approved

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Last modified October 13 21:59 EDT 2019. Contains 327981 sequences. (Running on oeis4.)