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 A050244 Numbers n such that 2^n + 3^n is a semiprime. 3
 3, 6, 7, 8, 10, 11, 12, 14, 16, 22, 32, 34, 38, 82, 83, 106, 128, 149, 218, 223, 334, 412, 436, 599, 647, 916, 1373, 4414, 7246, 8423, 10118, 10942, 15898 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Empirically, the smaller factor of 2^a(n) + 3^a(n) is a member of A294132 for all known terms. a(34) > 22000. - Hugo Pfoertner, Jul 29 2019 LINKS EXAMPLE a(1)=3 because 2^3+3^3 = 5 * 7 a(2)=6 because 2^6+3^6 = 13 * 61 a(3)=7 because 2^7+3^7 = 5 * 463 a(4)=8 because 2^8+3^8 = 17 * 401 a(5)=10 because 2^10+3^10 = 13 * 4621 a(6)=11 because 2^11+3^11 = 5 * 35839 a(7)=12 because 2^12+3^12 = 97 * 5521 a(8)=14 because 2^14+3^14 = 13 * 369181 a(9)=16 because 2^16+3^16 = 3041 * 14177 a(10)=22 because 2^22+3^22 = 13 * 2414250301 a(11)=32 because 2^32+3^32 = 1153 * 1607133116929 a(12)=34 because 2^34+3^34 = 13 * 1282861452271981 a(13)=38 because 2^38+3^38 = 13 * 103911691734684541 a(14)=82 because 2^82+3^82 = 13 * 102329189594547549657540565413396038701 a(15)=83 because 2^83+3^83 = 5 * 798167678837469920188160718521149336927 a(16)=106 because 2^106+3^106 = 13 * 28900785585664327723593061693364968422740414514061 a(17)=128 because 2^128+3^128 = 257 * 45876204582640401445607833244277975113391731388650867226881 a(18)=149 because 2^149+3^149 = 5 * 24665899002341798194980052306171212216360861465143461865961807325057879 CROSSREFS Cf. A001358, A007689, A082101, A294132. Sequence in context: A168114 A220656 A324143 * A295566 A266986 A047283 Adjacent sequences:  A050241 A050242 A050243 * A050245 A050246 A050247 KEYWORD nonn,more,hard AUTHOR Hugo Pfoertner, May 08 2003 EXTENSIONS Corrected and extended by Hugo Pfoertner, May 12 2003 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Dec 30 2007 5 more terms from Sean A. Irvine, Nov 05 2009 a(33) from Hugo Pfoertner, Jul 29 2019 STATUS approved

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Last modified October 16 02:52 EDT 2019. Contains 328038 sequences. (Running on oeis4.)