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 A181518 a(n) is the number for which 2^A181516(n)||(2*a(n))! 2
 2, 4, 7, 11, 13, 16, 22, 25, 28, 35, 37, 38, 41, 47, 50, 52, 56, 59, 64, 67, 70, 76, 88, 93, 97, 98, 100, 117, 122, 133, 137, 140, 143, 148, 158, 171, 176, 179, 182, 186, 193, 196, 200, 203, 213, 218, 223, 227, 233, 234, 236, 242, 247, 248, 253, 262, 280, 290, 299 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS MAPLE isA011371 := proc(n) option remember; local k, a; for k from 0 do a := A011371(k) ; if a > n then return false; elif a = n then return true; end if; end do: end proc: A181516 := proc(n) option remember; local a; if n = 1 then 3; else for a from procname(n-1)+1 do if isprime(a) then if isA011371(a) then return a; end if; end if; end do; end if; end proc: A181518 := proc(n) for m from 1 do if A011371(m) = A181516(n) then return m/2 ; end if; end do: end proc: # R. J. Mathar, Nov 04 2010 CROSSREFS Sequence in context: A229618 A087285 A107791 * A262231 A191323 A307207 Adjacent sequences:  A181515 A181516 A181517 * A181519 A181520 A181521 KEYWORD nonn,uned AUTHOR Vladimir Shevelev, Oct 26 2010 EXTENSIONS Corrected (88 inserted, 129 replaced by 179) and extended beyond 227 by R. J. Mathar, Nov 04 2010 STATUS approved

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Last modified January 22 10:06 EST 2021. Contains 340362 sequences. (Running on oeis4.)