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A211344 Atomic Boolean functions interpreted as binary numbers. 2
1, 3, 5, 15, 51, 85, 255, 3855, 13107, 21845, 65535, 16711935, 252645135, 858993459, 1431655765, 4294967295, 281470681808895, 71777214294589695, 1085102592571150095, 3689348814741910323, 6148914691236517205 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
Row n of the triangle shows the atoms among n-ary Boolean functions:
1 01
3 5 0011 0101
15 51 85 00001111 00110011 01010101
Often n-ary x_k = T(n,k), e.g. for 2-ary functions x_1=0011, x_2=0101 and for 3-ary functions x_1=00001111, x_2=00110011, x_3=01010101.
An easier generalized way is the enumeration from right to left (preferably from x_0) so that n-ary x_k = T(n,n-k). As numbers in the diagonals on the right have the same bit pattern this goes well together with the infinitary definition of atomic formulas as x_k = 1/A000215(k) = 1/(2^2^k+1) in binary:
2-ary x_0=0101=5, 3-ary x_0=01010101=85, infinitary x_0=1/3=.010101...
2-ary x_1=0011=3, 3-ary x_1=00110011=51, infinitary x_1=1/5=.001100110011...
LINKS
Tilman Piesk, Atomic Boolean functions in Sierpinski triangle (Wikimedia Commons)
FORMULA
PROG
(MATLAB)
Seq = sym(zeros(55, 1)) ;
Filledlines = 0 ;
for m=1:10
for n=1:m
Sum = sym(0) ;
for k=0:2^m-1
if mod( floor( k/2^(m-n) ) , 2) == 0
Sum = Sum + 2^sym(k) ;
end
end
Seq( Filledlines + n ) = Sum ;
end
Filledlines = Filledlines + m ;
end
(Python)
from itertools import count, islice
def A211344_gen(): # generator of terms
return (sum((bool(~(m:=(1<<t)-(1<<k)-1)&m-i)^1)<<i for i in range((1<<t)-(1<<k))) for t in count(1) for k in range(t-1, -1, -1))
A211344_list = list(islice(A211344_gen(), 20)) # Chai Wah Wu, May 03 2023
CROSSREFS
A001317, A089633, A051179 (left diagonal)
Sequence in context: A103043 A018601 A190733 * A006394 A018650 A177814
KEYWORD
nonn,tabl
AUTHOR
Tilman Piesk, Jul 24 2012
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)