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A085745
Numbers m such that 2^m + m is a semiprime.
4
2, 11, 23, 34, 59, 69, 87, 95, 119, 123, 129, 171, 197, 239, 341, 425, 455, 471, 515, 519, 635, 765, 959, 1115, 1181, 1210
OFFSET
1,1
COMMENTS
a(27) >= 1239. If 1239 is not a term then a(27) = 1275. - Amiram Eldar, Oct 26 2024
FORMULA
a(n) = 2*k <=> A089535(n) is even <=> A089536(n) = 2 <=> A089537(n) = 4^k/2 + k, and for any prime of this form, there is a term a(n) = 2*k in this sequence. - M. F. Hasler, Oct 08 2009
MATHEMATICA
Select[Range[1300], PrimeOmega[2^#+#]==2&] (* Harvey P. Dale, Dec 18 2014 *)
CROSSREFS
Sequences A165767, A165768, A165769 are the analog for 2^n-n. - M. F. Hasler, Oct 08 2009
Sequence in context: A218255 A256481 A373225 * A106856 A045387 A103255
KEYWORD
nonn,more,changed
AUTHOR
Jason Earls, Jul 21 2003
EXTENSIONS
More terms from Ray Chandler, Nov 08 2003
a(15) from Donovan Johnson, Mar 06 2008
a(16)-a(26) from Sean A. Irvine, Oct 27 2009
Offset changed to 1 by Jinyuan Wang, Jul 30 2021
STATUS
approved