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A076770 Even numbers representable as the sum of two odd composites. 2
18, 24, 30, 34, 36, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If n is even and n > 38, at least one of (n-15), (n-25), (n-35) is an odd number divisible by 3 and greater than 3. So every even number > 38 is a term. [Jack Brennen]

LINKS

Table of n, a(n) for n=1..60.

EXAMPLE

40 can be represented as 15+25 where 15 and 25 are both composite numbers, so 40 is a term.

PROG

(PARI) v=vector(5000); vc=1; forstep (n=9, 300, 2, if (isprime(n), continue, forstep (j=9, 300, 2, if (isprime(j), continue, x=n+j; fl=true; for (i=1, vc, if (v[i]==x, fl=false; break)); if (fl==true, v[vc]=x; vc++))))); print(vc); v=vecsort(vecextract(v, concat("1..", vc-1)))

CROSSREFS

Cf. A118081.

Sequence in context: A086473 A271327 A243539 * A105679 A160810 A076771

Adjacent sequences: A076767 A076768 A076769 * A076771 A076772 A076773

KEYWORD

nonn

AUTHOR

Jon Perry, Nov 14 2002

EXTENSIONS

Corrected by Don Reble, Nov 20 2006

STATUS

approved

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Last modified February 8 00:05 EST 2023. Contains 360133 sequences. (Running on oeis4.)