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A154865
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Numbers n such that smallest digit of n is prime and the smallest digit of prime(n) is also prime.
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0
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2, 3, 22, 23, 25, 52, 55, 56, 57, 59, 62, 72, 73, 75, 77, 78, 85, 332, 333, 334, 336, 337, 338, 342, 345, 346, 348, 352, 354, 355, 356, 357, 363, 364, 365, 366, 367, 372, 373, 375, 376, 378, 382, 383, 384, 385, 386, 388, 389, 392, 393, 398, 423, 424, 425, 426
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| If prime(n=2)=3, 2=prime and 3=prime, then 2=a)1). If prime(n=3)=5, 3=prime and 5=prime, then 3=a(2). If prime(n=22)=79, 2=2=prime and 9>7=prime, then 22=a(3). If prime(n=23)=83, 3>2=prime and 8>3=prime, then 23=a(4). If prime(n=25)=97, 5>2=prime and 9>7=prime, then 25=a(5). If prime(n=52)=239, 5>2=prime and 9>3>2=prime, then 52=a(6), etc.
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CROSSREFS
| Cf. A000027, A000040.
Sequence in context: A084796 A084797 A163902 * A032810 A062921 A083178
Adjacent sequences: A154862 A154863 A154864 * A154866 A154867 A154868
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KEYWORD
| nonn,base
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AUTHOR
| Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jan 16 2009
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EXTENSIONS
| 335 replaced by 334, keyword:base added - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 29 2010
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