A376843 Numbers k such that Omega(k + Omega(k)) = Omega(k) + Omega(Omega(k)), where Omega = A001222.

1, 2, 6, 10, 25, 26, 60, 74, 78, 115, 122, 123, 140, 145, 146, 147, 153, 156, 169, 186, 195, 205, 207, 220, 222, 231, 245, 253, 259, 273, 314, 323, 325, 341, 345, 348, 355, 361, 369, 386, 387, 427, 438, 453, 473, 481, 505, 507, 529, 536, 537, 553, 554, 555, 559, 561, 573, 582, 618, 620, 626, 635

Offset

1,2

Comments

Includes semiprimes k such that k + 2 is a triprime.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(5) = 25 is a term because Omega(25) = 2, Omega(2) = 1 and Omega(25 + 2) = Omega(27) = 3 = 2 + 1.

Maple

filter:= proc(k) uses numtheory; local s;
 s:= bigomega(k);
   bigomega(k+s) = s + bigomega(s)
end proc:
select(filter, [$1..1000]);

Crossrefs

Cf. A001222, A001358, A014612, A376830, A376831, A376844, A376848, A376849, A376851.

Sequence in context: A200220 A188224 A104142 * A258143 A369290 A079713

Adjacent sequences: A376840 A376841 A376842 * A376844 A376845 A376846

Keyword

nonn

Author

Robert Israel, Oct 06 2024

Status

approved