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A226368
Numbers k such that Omega(k) = Omega(2^k + 1), where Omega = A001222 is the number of prime factors counted with multiplicity.
0
2, 6, 36, 44, 52, 60, 72, 88, 112, 116, 136, 140, 152, 184, 288, 292, 320, 352, 388, 400, 404, 536, 544, 584, 632, 796, 844, 928, 1072, 1136
OFFSET
1,1
COMMENTS
At the moment, the least candidate for a(31) is 1168 = 2^4 * 73; the entry for 2^1168 + 1 on factordb.com has 3 prime factors and 1 composite cofactor with 326 decimal digits. - Lucas A. Brown, Mar 19 2024
FORMULA
{k: A054992(k) = A001222(k)}.
PROG
(PARI) is(n)=bigomega(2^n+1)==bigomega(n) \\ Charles R Greathouse IV, Mar 18 2014
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Irina Gerasimova, Jun 05 2013
EXTENSIONS
More terms from Jon E. Schoenfield, Sep 01 2013
a(29) added using factordb.com by Daniel Suteu, Jan 21 2023
a(30) added using factordb.com by Lucas A. Brown, Mar 19 2024
STATUS
approved