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 A248704 Smallest prime such that the n preceding prime gaps are strictly decreasing and the n subsequent prime gaps strictly increasing. 4
 3, 19, 1429, 25243, 340577, 1107791 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Abhiram R Devesh, Python code for generating strict valley primes EXAMPLE a(3)=1429 is in the middle of the sequence of successive primes [1409, 1423, 1427, 1429, 1433, 1439 , 1447] which have prime gaps [14, 4, 2, 4, 6, 8], and 14>4>2 is strictly decreasing and 4<6<8 is strictly increasing. MAPLE A248704 := proc(n)     local glist, p, wrks, s ;     if n = 0 then         return ;     else         s := n+1 ;         p := ithprime(s) ;         glist := [seq(ithprime(i+1)-ithprime(i), i=1..2*n)] ;         while true do             wrks := true;             for i from 1 to n-1 do                 if glist[i] <= glist[i+1] then                     wrks := false;                     break;                 end if;             end do:             if wrks then                 for i from n+1 to 2*n-1 do                     if glist[i] >= glist[i+1] then                         wrks := false;                         break;                     end if;                 end do:             end if;             if wrks then                 return p;             end if;             p := nextprime(p) ;             s := s+1 ;             glist := subsop(1=NULL, glist) ;             glist := [op(glist), ithprime(s+n)-ithprime(s+n-1)] ;         end do:     end if; end proc: # R. J. Mathar, Dec 04 2014 CROSSREFS Cf. A248701, A248702, A248703. Sequence in context: A114301 A258669 A192340 * A098796 A120563 A182344 Adjacent sequences:  A248701 A248702 A248703 * A248705 A248706 A248707 KEYWORD nonn,more AUTHOR Abhiram R Devesh, Oct 12 2014 STATUS approved

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Last modified July 16 04:26 EDT 2019. Contains 325064 sequences. (Running on oeis4.)