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A369662
Numbers k whose arithmetic derivative k' is of the form 4m+2, and k' has an odd number of prime factors.
4
65, 77, 135, 141, 161, 185, 201, 209, 221, 301, 305, 315, 321, 341, 351, 365, 377, 381, 413, 437, 453, 481, 485, 495, 497, 501, 537, 545, 589, 649, 681, 689, 717, 721, 729, 735, 737, 745, 749, 785, 789, 849, 855, 893, 901, 905, 917, 921, 975, 989, 999, 1035, 1037, 1073, 1081, 1101, 1121, 1133, 1141, 1157, 1165
OFFSET
1,1
COMMENTS
Equally, numbers k whose arithmetic derivative k' is congruent to 2 modulo 4 and A276085(k') is congruent to 1 modulo 4.
A003415((1/2)*A003415(a(n))) is always even.
LINKS
PROG
(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
isA369662(n) = { my(d=A003415(n)); (2==(d%4) && (bigomega(d)%2)); };
CROSSREFS
Setwise difference A327862 \ A369661.
Subsequences: A369664 (terms of the form 4m+1).
Sequence in context: A060877 A113688 A364028 * A369664 A214484 A159758
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 06 2024
STATUS
approved