A084424 Odd numbers having odd numbers of prime factors, odd sums of prime factors and odd sums of decimal digits.

3, 5, 7, 23, 27, 29, 41, 43, 47, 61, 67, 83, 89, 113, 131, 137, 139, 151, 157, 173, 179, 191, 193, 195, 197, 199, 223, 227, 229, 241, 243, 263, 269, 281, 283, 285, 311, 313, 317, 331, 337, 353, 357, 359, 373, 379, 397, 399, 401, 409, 421, 429, 443, 449, 461

Offset

1,1

Comments

A020639(a(n)), A001221(a(n)), A001222(a(n)), A008472(a(n)), A001414(a(n)) and A007953(a(n)) are all odd.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

9675 is odd, 9675 = 3^2 * 5^2 * 43: omega=3, Omega=5, sopf=3+5+43=51, sopfr=3+3+5+5+43=59 and SumOfDigits=9+6+7+5=27, therefore 9675 is a term.

Mathematica

odQ[n_]:=And@@OddQ[{PrimeOmega[n], Total[IntegerDigits[n]], Total[ Transpose[ FactorInteger[n]][[1]]]}]; Select[Range[1, 501, 2], odQ] (* Harvey P. Dale, Jan 09 2014 *)

Crossrefs

Sequence in context: A171015 A244571 A269721 * A137978 A155780 A296922

Adjacent sequences: A084421 A084422 A084423 * A084425 A084426 A084427

Keyword

nonn,base

Author

Reinhard Zumkeller, Jun 27 2003

Status

approved