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 A182180 Semiprimes that become prime when their digits are sorted into nonincreasing order. 1
 14, 34, 35, 38, 118, 119, 121, 133, 134, 142, 143, 145, 146, 166, 194, 214, 215, 218, 314, 334, 341, 346, 358, 361, 365, 377, 386, 395, 398, 413, 415, 437, 451, 473, 514, 517, 538, 583, 614, 634, 635, 671, 734, 737, 778, 779, 791, 799, 818, 835, 838, 878, 893 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Suggested by Kevin L. Schwartz. LINKS Alois P. Heinz, Table of n, a(n) for n = 1..1000 EXAMPLE a(10) = 121 = 11*11, which becomes the prime 211 when its digits are sorted into nonincreasing order. MAPLE h:= proc(m) local k; for k from m+1 while isprime(k) or             add(i[2], i=ifactors(k)[2])<>2 do od; k     end: a:= proc(n) option remember; local k;       k:= h(a(n-1));       do if isprime(parse(cat(sort(convert(k, base, 10), `>`)[])))             then return k else k:=h(k) fi       od     end: a(0):=0: seq(a(n), n=1..80);  # Alois P. Heinz, Apr 23 2012 CROSSREFS Cf. A000040, A001358, A115670 Semiprimes (A001358) whose digit reversal is prime, A182150 Semiprimes that are also semiprime when their digits are sorted into nondecreasing order. Sequence in context: A065933 A276715 A115670 * A112878 A175559 A158899 Adjacent sequences:  A182177 A182178 A182179 * A182181 A182182 A182183 KEYWORD nonn,base,easy AUTHOR Jonathan Vos Post, Apr 23 2012 EXTENSIONS More terms from Alois P. Heinz, Apr 23 2012 STATUS approved

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Last modified December 1 01:37 EST 2021. Contains 349426 sequences. (Running on oeis4.)