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%I #27 Nov 21 2018 00:35:05
%S 9,119,129,139,149,159,169,179,189,190,191,192,193,194,195,196,197,
%T 198,199,229,239,249,259,269,279,289,290,291,292,293,294,295,296,297,
%U 298,299,339,349,359,369,379,389,390,391,392,393,394,395,396
%N 9-ish numbers (A011539) which are not lunar primes (A087097).
%C Three and four digit 9ish numbers are lunar primes iff the smallest digit is strictly smaller than the first and the last digit. This is no longer true from 10109 = 109 x 109 on (where x = lunar product).
%H M. F. Hasler, <a href="/A087984/b087984.txt">Table of n, a(n) for n = 1..10000</a>
%H D. Applegate, <a href="/A087061/a087061.txt">C program for lunar arithmetic and number theory</a>
%H D. Applegate, M. LeBrun and N. J. A. Sloane, <a href="http://arxiv.org/abs/1107.1130">Dismal Arithmetic</a>, preprint, arxiv:1107.1130, July 2011. [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing.]
%H D. Applegate, M. LeBrun, N. J. A. Sloane, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL14/Sloane/carry2.html">Dismal Arithmetic</a>, J. Int. Seq. 14 (2011) # 11.9.8.
%H <a href="/index/Di#dismal">Index entries for sequences related to dismal (or lunar) arithmetic</a>
%F A011539 \ A087097. - _M. F. Hasler_, Nov 19 2018
%o From _M. F. Hasler_, Nov 19 2018: (Start)
%o (PARI) A087984=setminus(A011539, A087097)
%o A087984=[9]; for(L=3,4,forvec(d=vector(L,i,[i==1,9]),vecmax(d)==9&&vecmin(d)>=min(d[1],d[L])&&A087984=concat(A087984,fromdigits(d)))) \\ terms with < 5 digits
%o (PARI) is_A087984(n)=vecmax(digits(n))=9&&!is_A087097(n) \\ (End)
%Y Cf. A011539, A087097. A133626 and A134211 are subsequences.
%K nonn,base
%O 1,1
%A _David Applegate_ and _N. J. A. Sloane_, Oct 30 2003
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