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 A024675 Average of two consecutive odd primes. 83
 4, 6, 9, 12, 15, 18, 21, 26, 30, 34, 39, 42, 45, 50, 56, 60, 64, 69, 72, 76, 81, 86, 93, 99, 102, 105, 108, 111, 120, 129, 134, 138, 144, 150, 154, 160, 165, 170, 176, 180, 186, 192, 195, 198, 205, 217, 225, 228, 231, 236, 240, 246, 254, 260, 266, 270, 274, 279, 282, 288, 300 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sometimes called interprimes. Where local maxima of A072681 occur: A072681(a(n))=A074927(n+1). - Reinhard Zumkeller, Mar 04 2009 Never prime, for that would contradict the definition. - Jon Perry, Dec 05 2012 A subset of A145025, obtained from that sequence by omitting the primes (which are barycenter of their neighboring primes). - M. F. Hasler, Jun 01 2013 LINKS T. D. Noe, Table of n, a(n) for n = 1..10000 Eric Weisstein's World of Mathematics, Interprime FORMULA a(n) = (prime(n+1)+prime(n+2))/2 = A001043(n+1)/2. - Omar E. Pol, Feb 02 2012 Conjecture: a(n) = ceiling(sqrt(prime(n+1)*prime(n+2))). - Thomas Ordowski, Mar 22 2013 Equals A145025 \ A006562 = A145025 \ A000040. - M. F. Hasler, Jun 01 2013 MAPLE seq( ( (ithprime(x)+ithprime(x+1))/2 ), x=2..40); MATHEMATICA Plus @@@ Partition[Table[Prime[n], {n, 2, 100}], 2, 1]/2 ListConvolve[{1, 1}/2, Prime /@ Range[2, 70]] (* Jean-François Alcover, Jun 25 2013 *) Mean/@Partition[Prime[Range[2, 70]], 2, 1] (* Harvey P. Dale, Jul 28 2020 *) PROG (PARI) for(X=2, 50, print((prime(X)+prime(X+1))/2)) \\ Hauke Worpel (thebigh(AT)outgun.com), May 08 2008 (PARI) first(n)=my(v=primes(n+2)); vector(n, i, v[i+1]+v[i+2])/2 \\ Charles R Greathouse IV, Jun 25 2013 (Python) from sympy import prime def a(n): return (prime(n + 1) + prime(n + 2)) // 2 print([a(n) for n in range(1, 101)]) # Indranil Ghosh, Jul 11 2017 CROSSREFS Cf. A072568, A072569. Bisections give A058296, A079424. Sequence in context: A171845 A157124 A162735 * A274135 A163656 A100915 Adjacent sequences:  A024672 A024673 A024674 * A024676 A024677 A024678 KEYWORD nonn,nice,easy AUTHOR STATUS approved

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Last modified January 23 06:02 EST 2021. Contains 340384 sequences. (Running on oeis4.)