A155911 Composite numbers with final digit = number of prime factors (with multiplicity).

22, 24, 54, 62, 63, 82, 84, 96, 104, 122, 142, 153, 184, 202, 204, 216, 234, 262, 273, 294, 302, 333, 336, 343, 344, 362, 363, 364, 382, 405, 414, 416, 422, 423, 424, 444, 482, 483, 484, 486, 502, 542, 562, 564, 584, 603, 622, 644, 662, 663, 664, 675, 714

Offset

1,1

Comments

Almost all numbers in this sequence are 9 mod 10. The first such number is a(10589) = 124659. - Charles R Greathouse IV, Jan 02 2013

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Formula

a(n) ~ k*n log n/(log log n)^8 with k = 1/161280. - Charles R Greathouse IV, Jan 02 2013

Maple

A010879 := proc(n) n mod 10 ; end: A001222 := proc(n) numtheory[bigomega](n); end: for n from 4 to 2000 do if not isprime(n) then if A010879(n) = A001222(n) then printf("%d, ", n) ; fi; fi; od: # R. J. Mathar, Jan 31 2009

Mathematica

With[{upto=800}, Select[Complement[Range[upto], Prime[Range[ PrimePi[ upto]]]], Last[ IntegerDigits[#]] ==PrimeOmega[#]&]] (* Harvey P. Dale, Nov 29 2011 *)

Prog

(PARI) is(n)=!isprime(n) && bigomega(n)==n%10 \\ Charles R Greathouse IV, Jan 02 2013

Crossrefs

Cf. A002808.

Sequence in context: A244397 A138603 A181454 * A061411 A053779 A177734

Adjacent sequences: A155908 A155909 A155910 * A155912 A155913 A155914

Keyword

nonn,base

Author

Juri-Stepan Gerasimov, Jan 30 2009

Extensions

Extended by R. J. Mathar, Jan 31 2009

Name clarified by Harvey P. Dale and Charles R Greathouse IV, Jan 02 2013

Status

approved