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A181564
Semiprime convenient numbers.
0
4, 6, 9, 10, 15, 21, 22, 25, 33, 57, 58, 85, 93, 133, 177, 253
OFFSET
1,1
COMMENTS
This is to semiprimes A001358 as A140768 is to primes A000040. Because Euler's "numerus idoneus" (idoneal, or suitable, or convenient numbers) are finite, this subset is finite. Conjecture: this list is complete (see Weinberger's result and comment by Jud McCranie in A140768).
FORMULA
A000926 INTERSECTION A001358.
EXAMPLE
a(16) = A000926(50) = 253 = 11 * 23.
CROSSREFS
Sequence in context: A242664 A084662 A137167 * A119961 A122492 A178378
KEYWORD
nonn,fini
AUTHOR
Jonathan Vos Post, Jan 29 2011
STATUS
approved