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 A264721 Composite numbers that are greater than the average of their closest flanking primes. 4
 10, 16, 22, 27, 28, 35, 36, 40, 46, 51, 52, 57, 58, 65, 66, 70, 77, 78, 82, 87, 88, 94, 95, 96, 100, 106, 112, 121, 122, 123, 124, 125, 126, 130, 135, 136, 145, 146, 147, 148, 155, 156, 161, 162, 166, 171, 172, 177, 178, 187, 188, 189, 190, 196, 206, 207, 208 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Composite numbers that are nearer to the immediately next prime than to the immediately previous prime. Members of this sequence are the numbers C, necessarily composite, such that I_n < C < P_n+1, where P_n is the n-th odd prime and I_n the interprime (A024675) between P_n and P_n+1. Prime-free subsequence of A264719. LINKS Chris Boyd, Table of n, a(n) for n = 1..10000 EXAMPLE a(7) = 36 because 36 > (31 + 37)/2 = 34. MATHEMATICA Select[Range@ 208, And[CompositeQ@ #, # > (Abs@ NextPrime[#, -1] + NextPrime@ #)/2] &] (* Michael De Vlieger, Nov 22 2015 *) PROG (PARI) test(n)= {if(n-precprime(n-1)>nextprime(n+1)-n&&n>2&&!isprime(n), return(1), return(0))} for(i=1, 200, if(test(i), print1(i, ", "))) CROSSREFS Cf. A264719, A264720, A264722. Sequence in context: A238204 A242057 A245024 * A136799 A055987 A187397 Adjacent sequences:  A264718 A264719 A264720 * A264722 A264723 A264724 KEYWORD nonn,easy AUTHOR Chris Boyd, Nov 21 2015 STATUS approved

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Last modified August 13 06:22 EDT 2020. Contains 336442 sequences. (Running on oeis4.)