John Tyler Rascoe, <a href="/A367908/b367908_1.txt">Table of n, a(n) for n = 1..2000</a>

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OEIS Server: Installed first b-file as b367908.txt.

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John Tyler Rascoe, <a href="/A367908/b367908_1.txt">Table of n, a(n) for n = 1..2000</a>

(Python)

from itertools import count, islice, product

def bin_i(n): #binary indices

return([(i+1) for i, x in enumerate(bin(n)[2:][::-1]) if x =='1'])

def a_gen(): #generator of terms

for n in count(1):

p = list(product(*[bin_i(k) for k in bin_i(n)]))

x, c = len(p), 0

for j in range(x):

if len(set(p[j])) == len(p[j]): c += 1

if j+1 == x and c == 1: yield(n)

A367908_list = list(islice(a_gen(), 100)) # John Tyler Rascoe, Feb 10 2024

nonn,base

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These set-systems are counted by A367904, non-isomorphic A368099.

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approved

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