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A087984
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9-ish numbers (A011539) which are not lunar primes (A087097).
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4
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9, 119, 129, 139, 149, 159, 169, 179, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 229, 239, 249, 259, 269, 279, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 299, 339, 349, 359, 369, 379, 389, 390, 391, 392, 393, 394, 395, 396
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OFFSET
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1,1
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COMMENTS
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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).
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LINKS
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D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic, 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.]
D. Applegate, M. LeBrun, N. J. A. Sloane, Dismal Arithmetic, J. Int. Seq. 14 (2011) # 11.9.8.
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FORMULA
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PROG
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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
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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