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A369663
Numbers k of the form 4m+3, whose arithmetic derivative k' is of the form 4u+2, and k' has an even number of prime factors.
5
375, 459, 783, 819, 875, 1071, 1107, 1155, 1375, 1395, 1715, 1911, 1935, 1995, 2223, 2275, 2375, 2499, 2619, 2655, 2695, 2727, 2875, 2907, 2943, 3003, 3051, 3135, 3195, 3255, 3315, 3519, 3575, 3627, 3699, 3843, 3927, 3975, 4059, 4459, 4515, 4671, 4815, 4887, 4935, 4959, 5187, 5247, 5375, 5415, 5607, 5635, 5655
OFFSET
1,1
LINKS
PROG
(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
isA369663(n) = if(3!=(n%4), 0, my(d=A003415(n)); (2==(d%4) && !(bigomega(d)%2)));
CROSSREFS
Intersection of A004767 and A369661.
Subsequence of A369666.
Sequence in context: A093237 A269113 A268751 * A249550 A045200 A252071
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 06 2024
STATUS
approved