cp's OEIS Frontend

A151740 Composites that are the sum of two consecutive composite numbers.

%I A151740 #24 Feb 07 2024 01:28:12
%S A151740 10,14,22,26,34,38,46,49,51,55,58,62,65,69,74,77,82,86,91,94,99,106,
%T A151740 111,115,118,122,125,129,134,142,146,153,155,158,161,166,169,171,175,
%U A151740 178,183,185,187,189,194,202,206,209,214,218,221,226,231,235,237,243,245
%N A151740 Composites that are the sum of two consecutive composite numbers.
%C A151740 The even terms of this sequence are exactly twice the primes > 3. The odd terms are odd composites c for which the odd integer next to c/2 is not prime. - _M. F. Hasler_, Jun 16 2009
%C A151740 The English language can be ambiguous! What is meant here is: write down a list of the composite numbers 4,6,8,9,10,12,... Whenever the sum of two adjacent terms is composite, adjoin it to the sequence: 4+6=10, 6+8=14, 10+12=22, ... - _N. J. A. Sloane_, Nov 26 2019
%H A151740 Karl-Heinz Hofmann, <a href="/A151740/b151740.txt">Table of n, a(n) for n = 1..10000</a>
%t A151740 CompositeNext[n_]:=Module[{k=n+1},While[PrimeQ[k],k++ ];k]; q=6!;lst2={};Do[If[ !PrimeQ[n],c=CompositeNext[n];a2=n+c;If[ !PrimeQ[a2],AppendTo[lst2,a2]]],{n,q}];lst2 (* _Vladimir Joseph Stephan Orlovsky_, Jun 17 2009 *)
%t A151740 Module[{c=Select[Range[300],CompositeQ],s2},s2=Total/@Partition[c,2,1];Intersection[c,s2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Nov 27 2019 *)
%o A151740 (PARI) isA151740(n)= bittest(n,0) || return(isprime(n/2) && n>6); !isprime(bitor(n\2,1)) && !isprime(n) && n>1 \\ _M. F. Hasler_, Jun 16 2009
%o A151740 (Python)
%o A151740 from sympy import isprime, composite
%o A151740 print([totest for k in range(1,92) if not isprime(totest := composite(k) + composite(k+1))]) # _Karl-Heinz Hofmann_, Feb 06 2024
%Y A151740 Cf. A002808, A151741, A151742, A151743, A151744, A151745, A060254, A060327, A060339, A096785, A096787, A135170. - _M. F. Hasler_, Jun 16 2009
%Y A151740 Cf. A167611 (Essentially the same, except for initial term).
%K A151740 nonn
%O A151740 1,1
%A A151740 _Claudio Meller_, Jun 15 2009