

A155911


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


1



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
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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

JuriStepan 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



