

A235108


Semiprimes with digits in strictly decreasing order.


1



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

1,1


LINKS

Donovan Johnson, Table of n, a(n) for n = 1..159 (complete sequence)


PROG

(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


CROSSREFS

Cf. A001358, A108635, A108634, A135355.
Sequence in context: A135257 A118697 A118695 * A215478 A118693 A084668
Adjacent sequences: A235105 A235106 A235107 * A235109 A235110 A235111


KEYWORD

nonn,base,fini,full


AUTHOR

Colin Barker, Jan 03 2014


STATUS

approved



