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A050689 Sum of digits of composite a(n) equals number of its prime factors, with multiplicity. 8
12, 30, 32, 40, 102, 220, 240, 500, 600, 1002, 1012, 1104, 1152, 1210, 1320, 1500, 2001, 2002, 2020, 2040, 2120, 2240, 2300, 3010, 3040, 3300, 4032, 4100, 4320, 5100, 5200, 6400, 7000, 7200, 10001, 10002, 10011, 10030, 10040, 10080, 10140, 10220 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 322 terms from Michael Turniansky)

EXAMPLE

2002: 2+0+0+2 = 4 prime factors namely 2.7.11.13.

MATHEMATICA

Select[Range[10300], !PrimeQ[#]&&PrimeOmega[#]==Total[IntegerDigits[#]]&] (* Jayanta Basu, May 30 2013 *)

PROG

(APL (NARS200 dialect)) ⍸∊{(⍴π⍵)=+/(10⍴10)⊤⍵}¨⍳1E6 ⍝for the numbers through 1000000 Michael Turniansky Feb 13 2017

(PARI) isok(n) = sumdigits(n) == bigomega(n); \\ Michel Marcus, Feb 13 2017

CROSSREFS

Cf. A050690, A057531, A057532, A070274, A070275, A063737, A067077.

Sequence in context: A049725 A183723 A247152 * A144565 A115912 A083096

Adjacent sequences:  A050686 A050687 A050688 * A050690 A050691 A050692

KEYWORD

nonn,base,changed

AUTHOR

Patrick De Geest, Aug 15 1999

STATUS

approved

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Last modified April 29 01:04 EDT 2017. Contains 285604 sequences.