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A099482
Semiprimes of the form 2^k - k^2.
3
1927, 8023, 32543, 2096711, 8388079, 137438952103, 549755812367, 2199023253871, 8796093020359, 140737488353119, 562949953418911, 36028797018960943, 147573952589676408439, 37778931862957161703943
OFFSET
1,1
EXAMPLE
a(2) = 8023 because 8023 = 71*113 = 2^13 - 13^2 = 2^A099481(2) - A099481(2)^2.
MATHEMATICA
Select[Table[2^n - n^2, {n, 100}], PrimeOmega[#] == 2&] (* Vincenzo Librandi, Sep 21 2012 *)
CROSSREFS
Cf. A024012 2^n-n^2, A099481 2^k-k^2 is a semiprime, A072180 2^k-k^2 is prime, A075896 primes of the form 2^k-k^2.
Sequence in context: A283949 A133301 A258841 * A253337 A200435 A252108
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Oct 18 2004
STATUS
approved