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A128285 Numbers of the form m = p1 * p2 * p3 * p4 where for each d|m we have (d+m/d)/2 prime and p1 < p2 < p3 < p4 each prime. 5
1365, 4305, 10465, 11685, 15873, 27105, 31845, 35245, 50065, 54033, 58765, 74965, 84513, 91977, 95557, 95613, 96033, 104377, 113997, 114405, 117957, 118105, 126357, 127605, 136437, 170905, 197985, 209605, 215373, 226185, 248385, 277797 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

David A. Corneth, Table of n, a(n) for n = 1..3114

EXAMPLE

1365=3 * 5 * 7 * 13 and (3 * 5 * 7 * 13+1)/2, (3+5 * 7 * 13)/2, (5+3 * 7 * 13)/2, (7+3 * 5 * 13)/2, (13+3 * 5 * 7)/2, (3 * 5+7.13)/2, (3 * 7+5 * 13)/2, (3 * 13+5 * 7)/2 are all primes and 1365 is the smallest such integer which is the product of 4 primes, so 1365 is in the sequence.

CROSSREFS

Cf. A128281, A005383, A128283, A128284, A128286.

Subsequence of A046390.

Sequence in context: A043578 A004970 A234501 * A069310 A096117 A140936

Adjacent sequences:  A128282 A128283 A128284 * A128286 A128287 A128288

KEYWORD

nonn

AUTHOR

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

EXTENSIONS

New name from David A. Corneth, Jan 09 2021

STATUS

approved

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Last modified March 6 07:15 EST 2021. Contains 341842 sequences. (Running on oeis4.)