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A359784
Numbers k such that A358680(k) = 1 but A359781(k) = 0, where A359781 is the parity of Dirichlet inverse of the former (which is the characteristic function of the numbers with even arithmetic derivative).
6
16, 81, 128, 192, 225, 240, 320, 324, 336, 384, 441, 448, 528, 560, 624, 625, 640, 648, 704, 729, 816, 832, 880, 896, 900, 912, 972, 1024, 1040, 1088, 1089, 1104, 1215, 1216, 1225, 1232, 1360, 1392, 1408, 1456, 1472, 1488, 1520, 1521, 1620, 1664, 1701, 1764, 1776, 1800, 1840, 1856, 1904, 1920, 1944, 1968, 1984
OFFSET
1,1
PROG
(PARI)
A358680(n) = if(n<=1, 1, my(f=factor(n)); 0==((n*sum(i=1, #f~, f[i, 2]/f[i, 1]))%2));
memoA359780 = Map();
A359780(n) = if(1==n, 1, my(v); if(mapisdefined(memoA359780, n, &v), v, v = -sumdiv(n, d, if(d<n, A358680(n/d)*A359780(d), 0)); mapput(memoA359780, n, v); (v)));
A359781(n) = (A359780(n)%2);
isA359784(n) = (A358680(n)&&!(A359781(n)));
CROSSREFS
Setwise difference A235992\{0} \ A359783.
Setwise difference A359782 \ A235991.
Subsequence of A013929.
Cf. also A359767.
Sequence in context: A339596 A088040 A354799 * A346484 A065771 A320965
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 13 2023
STATUS
approved