A248147 - OEIS

A248147

Table read by rows: n-th row contains all consecutive subsets of the first n primes in their natural order.

2, 2, 3, 2, 3, 2, 3, 5, 2, 3, 3, 5, 2, 3, 5, 2, 3, 5, 7, 2, 3, 3, 5, 5, 7, 2, 3, 5, 3, 5, 7, 2, 3, 5, 7, 2, 3, 5, 7, 11, 2, 3, 3, 5, 5, 7, 7, 11, 2, 3, 5, 3, 5, 7, 5, 7, 11, 2, 3, 5, 7, 3, 5, 7, 11, 2, 3, 5, 7, 11, 2, 3, 5, 7, 11, 13, 2, 3, 3, 5, 5, 7, 7, 11

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OFFSET

1,1

COMMENTS

A000292(n) = length of n-th row, whereas A000217(n) = number of all consecutive subsets of numbers 1..n;

T(n,k) = A000040(A248141(n,k)), 1 <= k <= A000292(n).

LINKS

Reinhard Zumkeller, Rows n = 1..20 of triangle, flattened

EXAMPLE

. 1: 2

. 2: 2,3,2,3

. 3: 2,3,5,2,3,3,5,2,3,5

. 4: 2,3,5,7,2,3,3,5,5,7,2,3,5,3,5,7,2,3,5,7

. 5: 2,3,5,7,11,2,3,3,5,5,7,7,11,2,3,5,3,5,7,5,7,11,2,3,5,7,3,5,7,11,...

rows concatenated from:

. 1: [2]

. 2: [2] [3] [2,3]

. 3: [2] [3] [5] [2,3] [3,5] [2,3,5]

. 4: [2] [3] [5] [7] [2,3] [3,5] [5,7] [2,3,5] [3,5,7] [2,3,5,7]

. 5: [2] [3] [5] [7] [11] [2,3] [3,5] [5,7] [7,11] [2,3,5] [3,5,7] ...

PROG

(Haskell)

import Data.List (group)

a248147 n k = a248147_tabf !! (n-1) !! (k-1)

a248147_row n = a248147_tabf !! (n-1)

a248147_tabf = map concat psss where

psss = iterate f [[2]] where

f pss = group (h $ last pss) ++ map h pss

h ws = ws ++ [a151800 $ last ws]

CROSSREFS

Cf. A151800, A000292, A000217, A248164, A248141.

Sequence in context: A099427 A059964 A308050 * A087458 A052180 A065151

Adjacent sequences: A248144 A248145 A248146 * A248148 A248149 A248150

KEYWORD

nonn,tabf

AUTHOR

Reinhard Zumkeller, Oct 02 2014

STATUS

approved