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A108635 Semiprimes with property that digits are in nonincreasing order. 1

%I #6 Dec 13 2015 01:02:16

%S 4,6,9,10,21,22,33,51,55,62,65,74,77,82,85,86,87,91,93,94,95,111,221,

%T 321,411,422,511,533,542,543,551,553,554,611,622,633,655,662,721,731,

%U 753,755,763,766,771,831,841,842,843,851,862,865,866,871,886,921,922

%N Semiprimes with property that digits are in nonincreasing order.

%e The semiprime 14 is missing because 4 > 1.

%t Select[Range[1000], Plus@@Last/@FactorInteger[ # ]\[Equal]2&&OrderedQ[Reverse[IntegerDigits[ # ]]]&]

%Y Cf. A108634.

%K nonn,base,easy,less

%O 1,1

%A _Zak Seidov_, Jun 14 2005

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Last modified April 24 22:17 EDT 2024. Contains 371964 sequences. (Running on oeis4.)