id:A054257 - OEIS Search Results

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Concatenation of n in base 10 down up to base 2 is prime, all numbers are interpreted as decimals.

+0
4

21, 117, 241, 283, 389, 517, 547, 627, 1219, 1223, 1247, 1285, 1287, 1323, 1467, 1505, 1591, 1599, 1689, 1713, 1817, 1961, 2203, 2309, 2377, 2607, 2837, 2847, 2899, 2911, 3227, 3261, 3499, 3823, 4007, 4069, 4183, 4347, 4403, 4473, 4507, 4535, 4637 (list; graph; listen)

	OFFSET	`0,1`
	EXAMPLE	`E.g. a(1)=21 -> 21{10}=23{9}=25{8}=30{7}=33{6}=41{5}=111{4}=210{3}=10101{2} -> 21232530334111121010101 is a prime.`
	CROSSREFS	`Cf. A054256, A054258.` `Sequence in context: A039456 A129135 A121628 this_sequence A079417 A074088 A044353` `Adjacent sequences: A054254 A054255 A054256 this_sequence A054258 A054259 A054260`
	KEYWORD	`nonn,base`
	AUTHOR	`Patrick De Geest (pdg(AT)worldofnumbers.com), Feb 15 2000.`

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.

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