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A235108
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Semiprimes with digits in strictly decreasing order.
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1
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4, 6, 9, 10, 21, 51, 62, 65, 74, 82, 85, 86, 87, 91, 93, 94, 95, 321, 542, 543, 721, 731, 753, 763, 831, 841, 842, 843, 851, 862, 865, 871, 921, 943, 951, 961, 965, 973, 974, 982, 985, 4321, 5321, 6431, 6541, 6542, 7421, 7431, 7531, 7543, 7631, 7642, 7651
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OFFSET
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1,1
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LINKS
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PROG
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(PARI)
list(lim)=my(v=List(), t); forprime(p=2, sqrt(lim), t=p; forprime(q=p, lim\t, listput(v, t*q))); vecsort(Vec(v)) \\ From A001358
isdecr(a) = {my(b=-1); until(a==0, if(a%10<=b, return(0)); b=a%10; a\=10); return(1)}
u=list(50000); s=[]; for(n=1, #u, if(isdecr(u[n]), s=concat(s, u[n]))); s
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CROSSREFS
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KEYWORD
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nonn,base,fini,full
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AUTHOR
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STATUS
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approved
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