A221264 Numbers having fewer distinct prime factors of form 4*k+1 than of 4*k+3.

3, 6, 7, 9, 11, 12, 14, 18, 19, 21, 22, 23, 24, 27, 28, 31, 33, 36, 38, 42, 43, 44, 46, 47, 48, 49, 54, 56, 57, 59, 62, 63, 66, 67, 69, 71, 72, 76, 77, 79, 81, 83, 84, 86, 88, 92, 93, 94, 96, 98, 99, 103, 105, 107, 108, 112, 114, 118, 121, 124, 126, 127, 129

Offset: 1

Author

Reinhard Zumkeller, Jan 07 2013

Keywords

• nonn
• easy

Comments

A005089(a(n)) < A005091(a(n)); A005094(a(n)) < 0.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A005089, A005091, A005094, A078613, A221265.

Programs

Haskell

a221264 n = a221264_list !! (n-1)
a221264_list = filter ((< 0) . a005094) [1..]

PARI

is_A221264(n)={#(n=vecsort(factor(n>>valuation(n,2))[,1]%4))&&n[(1+#n)\2]==3} \\ M. F. Hasler, Dec 17 2014