OFFSET
0,2
LINKS
John Tyler Rascoe, Python program.
EXAMPLE
In the set-system: {{2, 3, 5},{3, 4, 5},{1, 3},{2}} no element k appears more than k times, so it is counted under a(5) = 26672.
a(n) for n = 0..2 counts the following set-systems:
a(0) = 1: {}.
a(1) = 2: {}, {{1}}.
a(2) = 6: {}, {{1}}, {{2}}, {{1},{2}}, {{1,2}}, {{1,2},{2}}.
PROG
(Python) # see linked program
CROSSREFS
KEYWORD
nonn,more
AUTHOR
John Tyler Rascoe, Jul 08 2024
EXTENSIONS
a(7)-a(8) from Alois P. Heinz, Jul 09 2024
a(9) from Alois P. Heinz, Jul 15 2024
a(10)-a(12) from Christian Sievers, Jul 17 2024
STATUS
approved