login
This site is supported by donations to The OEIS Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A228019 Composite numbers whose sum of digits is a composite number. 2
4, 6, 8, 9, 15, 18, 22, 24, 26, 27, 28, 33, 35, 36, 39, 40, 42, 44, 45, 46, 48, 51, 54, 55, 57, 60, 62, 63, 64, 66, 68, 69, 72, 75, 77, 78, 80, 81, 82, 84, 86, 87, 88, 90, 91, 93, 95, 96, 99, 105, 108, 112, 114, 116, 117, 118, 121, 123, 125, 126, 129, 130, 132 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

87 is a term: 87 and 8+7=15 are composite.

PROG

(PARI) lista(N) = my(s); for(n=2, N, s=sumdigits(n); if(!isprime(n)&&!isprime(s)&&s>1, print1(n, ", ") ) ) \\ Joerg Arndt, Aug 04 2013

(PARI) list(N)=my(v=List(), s); forcomposite(n=4, N, s=sumdigits(n); if(s>1 && !isprime(s), listput(v, n))); Vec(v)  \\ Charles R Greathouse IV, Aug 13 2013

(MAGMA) [n: n in [4..200] | not IsPrime(n) and not IsPrime(&+Intseq(n))]; // Bruno Berselli, Aug 13 2013

CROSSREFS

Subsequence of A104211.

Sequence in context: A262389 A254755 A275624 * A228020 A163282 A095404

Adjacent sequences:  A228016 A228017 A228018 * A228020 A228021 A228022

KEYWORD

nonn,base,easy

AUTHOR

Derek Orr, Aug 02 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 19 17:45 EST 2019. Contains 319309 sequences. (Running on oeis4.)