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A085612
Triangle in which the n-th row contains n numbers (beginning with the smallest unused value) that have the same prime signature as the first entry on that row.
5
1, 2, 3, 4, 9, 25, 5, 7, 11, 13, 6, 10, 14, 15, 21, 8, 27, 125, 343, 1331, 2197, 12, 18, 20, 28, 44, 45, 50, 16, 81, 625, 2401, 14641, 28561, 83521, 130321, 17, 19, 23, 29, 31, 37, 41, 43, 47, 22, 26, 33, 34, 35, 38, 39, 46, 51, 55, 24, 40, 54, 56, 88, 104, 135, 136, 152
OFFSET
1,2
COMMENTS
Permutation of the natural numbers when the triangle is seen flattened, inverse = A226387, see also A224401. - Reinhard Zumkeller, Jun 05 2013
EXAMPLE
a(7) through a(10) = 5, 7, 11, 13 because 5 has not been used.
1;
2,3;
4,9,25;
5,7,11,13;
6,10,14,15,21;
8,27,125,343,1331,2197;
12,18,20,28,44,45,50;
16,81,625,2401,14641,28561,83521,130321;
PROG
(Haskell)
import Data.List ((\\))
a085612 n k = a085612_row n !! (k-1)
a085612_row n = a085612_tabf !! (n-1)
a085612_tabf = f 0 $ zip [1..] a046523_list where
f x zs'@(z:zs) = (map fst ys) : f (x + 1) (zs' \\ ys) where
ys = z : take x (filter ((== snd z) . snd) zs)
a085612_list = concat a085612_tabf
-- Reinhard Zumkeller, Jun 05 2013
(PARI) See Links section.
CROSSREFS
Cf. A085836.
Cf. A046523.
Sequence in context: A280054 A088220 A333431 * A073915 A076381 A282571
KEYWORD
nonn,tabl
AUTHOR
Alford Arnold, Jul 04 2003
EXTENSIONS
More terms from Ray Chandler, Aug 21 2003
STATUS
approved