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A050244 Numbers n such that 2^n + 3^n is a semiprime. 1

%I

%S 3,6,7,8,10,11,12,14,16,22,32,34,38,82,83,106,128,149,218,223,334,412,

%T 436,599,647,916,1373,4414,7246,8423,10118,10942

%N Numbers n such that 2^n + 3^n is a semiprime.

%e a(1)=3 because 2^3+3^3 = 5 * 7

%e a(2)=6 because 2^6+3^6 = 13 * 61

%e a(3)=7 because 2^7+3^7 = 5 * 463

%e a(4)=8 because 2^8+3^8 = 17 * 401

%e a(5)=10 because 2^10+3^10 = 13 * 4621

%e a(6)=11 because 2^11+3^11 = 5 * 35839

%e a(7)=12 because 2^12+3^12 = 97 * 5521

%e a(8)=14 because 2^14+3^14 = 13 * 369181

%e a(9)=16 because 2^16+3^16 = 3041 * 14177

%e a(10)=22 because 2^22+3^22 = 13 * 2414250301

%e a(11)=32 because 2^32+3^32 = 1153 * 1607133116929

%e a(12)=34 because 2^34+3^34 = 13 * 1282861452271981

%e a(13)=38 because 2^38+3^38 = 13 * 103911691734684541

%e a(14)=82 because 2^82+3^82 = 13 * 102329189594547549657540565413396038701

%e a(15)=83 because 2^83+3^83 = 5 * 798167678837469920188160718521149336927

%e a(16)=106 because 2^106+3^106 = 13 * 28900785585664327723593061693364968422740414514061

%e a(17)=128 because 2^128+3^128 = 257 * 45876204582640401445607833244277975113391731388650867226881

%e a(18)=149 because 2^149+3^149 = 5 * 24665899002341798194980052306171212216360861465143461865961807325057879

%Y Cf. A001358, A082101.

%K more,nonn

%O 1,1

%A _Hugo Pfoertner_, May 08 2003

%E Corrected and extended by _Hugo Pfoertner_, May 12 2003

%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Dec 30 2007

%E 5 more terms from _Sean A. Irvine_, Nov 05 2009

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Last modified July 19 03:54 EDT 2019. Contains 325144 sequences. (Running on oeis4.)