A268381 Numbers having at least the same number of prime factors of the form 4*k+1 than of the form 4*k+3, when counted with multiplicity.

1, 2, 4, 5, 8, 10, 13, 15, 16, 17, 20, 25, 26, 29, 30, 32, 34, 35, 37, 39, 40, 41, 50, 51, 52, 53, 55, 58, 60, 61, 64, 65, 68, 70, 73, 74, 75, 78, 80, 82, 85, 87, 89, 91, 95, 97, 100, 101, 102, 104, 106, 109, 110, 111, 113, 115, 116, 119, 120, 122, 123, 125, 128, 130, 136, 137, 140, 143, 145, 146, 148, 149, 150

Offset

1,2

Comments

Numbers n for which A083025(n) >= A065339(n) or equally, for which A079635(n) >= 0.

Closed under multiplication.

Links

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

Mathematica

Position[Array[Map[Length, {Select[#, Mod[#, 4] == 1 &], Select[#, Mod[#, 4] == 3 &]}] &@ Flatten@ Apply[Table[#1, {#2}] &, FactorInteger@ #, 1] &, {150}], {a_, b_} /; a >= b] // Flatten (* Michael De Vlieger, Feb 05 2016 *)

Prog

(Scheme, with Antti Karttunen's IntSeq-library)
(define A268381 (MATCHING-POS 1 1 (COMPOSE not negative? A079635)))

Crossrefs

Complement: A268380.

Disjoint union of A072202 and A268379.

Cf. A079635, A065339, A083025.

Sequence in context: A173509 A007729 A174868 * A186349 A304360 A072437

Adjacent sequences: A268378 A268379 A268380 * A268382 A268383 A268384

Keyword

nonn

Author

Antti Karttunen, Feb 05 2016

Status

approved