

A248147


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


5



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



OFFSET

1,1


COMMENTS

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


LINKS



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 !! (n1) !! (k1)
a248147_row n = a248147_tabf !! (n1)
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



KEYWORD

nonn,tabf


AUTHOR



STATUS

approved



