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A128284 a[n]= is the n-th smallest product of 3 odd primes m=p1*p2*p3, such that (d+m/d)/2 are all primes for each d dividing m. 4
105, 165, 273, 345, 357, 385, 777, 897, 1045, 1173, 1353, 1653, 1677, 1705, 2193, 2233, 2373, 2905, 3157, 3237, 3333, 3417, 3445, 3553, 3565, 3945, 4053, 4585, 4953, 5665, 5817, 6097, 6513, 6693, 7077, 7833, 8437, 8565, 8845, 10153, 11005, 11433 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..42.

EXAMPLE

165=3.5.11 and (3.5.11+1)/2=83, (3+5.7)/2=19, (5+3.7)/2=13, (7+3.5)/2=11 are all primes and 165 is the 2nd smallest number of such form, so a[2]=165

CROSSREFS

Cf. A128281, A005383, A128283, A128285, A128286.

Sequence in context: A046405 A128278 A234103 * A161962 A046887 A026066

Adjacent sequences:  A128281 A128282 A128283 * A128285 A128286 A128287

KEYWORD

nonn

AUTHOR

Kok Seng Chua (chuakokseng(AT)hotmail.com), Mar 05 2007

STATUS

approved

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Last modified February 26 21:58 EST 2020. Contains 332295 sequences. (Running on oeis4.)