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A340370
a(n) = 1 if the odd part of n is a squarefree semiprime, 0 otherwise.
3
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1
OFFSET
1
FORMULA
a(n) = A280710(A000265(n)).
PROG
(PARI)
A000265(n) = (n>>valuation(n, 2));
A280710(n) = (bigomega(n)==2*issquarefree(n)); \\ After code in A280710.
CROSSREFS
Characteristic function of A340380.
Cf. also A340371.
Sequence in context: A353481 A353677 A353676 * A216038 A011728 A297043
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 06 2021
STATUS
approved