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A161920
a(n) = A161511(A004760(n)).
3
1, 2, 4, 3, 6, 5, 6, 4, 8, 7, 8, 6, 9, 7, 8, 5, 10, 9, 10, 8, 11, 9, 10, 7, 12, 10, 11, 8, 12, 9, 10, 6, 12, 11, 12, 10, 13, 11, 12, 9, 14, 12, 13, 10, 14, 11, 12, 8, 15, 13, 14, 11, 15, 12, 13, 9, 16, 13, 14, 10, 15, 11, 12, 7, 14, 13, 14, 12, 15, 13, 14, 11, 16, 14, 15, 12, 16
OFFSET
1,2
COMMENTS
a(n) gives the one-based position of the first nonzero term on the row n-1 of A126441.
Sequence A016116 can be used to identify the extracted subsequence by computing the number of terms to alternately extract and skip. [This comment is from the original submitter. I don't understand it. - Antti Karttunen, Oct 12 2009]
PROG
(Python)
def A161920(n):
a, b = 1+(m:=n-1).bit_length(), 1
for i, j in enumerate(bin(m)[:1:-1], 1):
if int(j):
a += i-b
b += 1
return a # Chai Wah Wu, Jul 26 2023
CROSSREFS
a(n) = A161511(A004760(n)) = 1 + A055941(n-1) + A029837(n).
Sequence in context: A182298 A182732 A119477 * A366943 A366945 A278512
KEYWORD
nonn
AUTHOR
Alford Arnold, Jun 24 2009
EXTENSIONS
Edited and extended by Antti Karttunen, Oct 12 2009
STATUS
approved