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A335346 Lesser of two consecutive semiprimes whose sum and difference are also semiprimes. 1
51, 65, 87, 111, 129, 146, 209, 249, 278, 291, 305, 335, 377, 407, 447, 485, 489, 497, 629, 681, 699, 749, 767, 785, 917, 939, 951, 989, 1007, 1018, 1037, 1115, 1177, 1191, 1257, 1397, 1457, 1469, 1497, 1509, 1546, 1565, 1594, 1707, 1731, 1757, 1799, 1945, 1977 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Intersection of A272306 and A272307.
LINKS
EXAMPLE
51 = A272306(8) = A272307(3), 65 = A272306(10) = A272307(5).
MAPLE
b:= 4:
Res:= NULL: count:= 0:
while count < 100 do
a:= b;
for k from b+1 do if numtheory:-bigomega(k) = 2 then b:= k; break fi od:
if numtheory:-bigomega(b-a) = 2 and numtheory:-bigomega(b+a) = 2 then
count:= count+1; Res:= Res, a;
fi
od:
Res; # Robert Israel, Nov 10 2022
PROG
(PARI) psp=4; for(k=6, 2000, if(bigomega(k)==2, if(bigomega(k-psp)==2, if(bigomega(k+psp)==2, print1(psp, ", "))); psp=k)) \\ Hugo Pfoertner, Jun 03 2020
CROSSREFS
Sequence in context: A206525 A216055 A034819 * A118147 A015863 A232105
KEYWORD
nonn
AUTHOR
Zak Seidov, Jun 02 2020
STATUS
approved

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Last modified July 16 10:51 EDT 2024. Contains 374345 sequences. (Running on oeis4.)