A369664 Numbers k of the form 4m+1, whose arithmetic derivative k' is of the form 4u+2, and k' has an odd number of prime factors.

65, 77, 141, 161, 185, 201, 209, 221, 301, 305, 321, 341, 365, 377, 381, 413, 437, 453, 481, 485, 497, 501, 537, 545, 589, 649, 681, 689, 717, 721, 729, 737, 745, 749, 785, 789, 849, 893, 901, 905, 917, 921, 989, 1037, 1073, 1081, 1101, 1121, 1133, 1141, 1157, 1165, 1169, 1189, 1205, 1253, 1261, 1293, 1313, 1317

Offset: 1

Author

Antti Karttunen, Feb 06 2024

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000

Crossrefs

Intersection of A016813 and A369662.

Subsequence of A369666.

Cf. A003415, A351228.

Programs

PARI

A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
isA369664(n) = if(1!=(n%4), 0, my(d=A003415(n)); (2==(d%4) && (bigomega(d)%2)));