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A234431 Numbers that are the sum of 2 successive evil numbers (A001969). 3

%I

%S 3,8,11,15,19,22,27,32,35,38,43,47,51,56,59,63,67,70,75,79,83,88,91,

%T 94,99,104,107,111,115,118,123,128,131,134,139,143,147,152,155,158,

%U 163,168,171,175,179,182,187,191,195,200,203,207,211,214,219,224,227,230,235,239,243,248,251

%N Numbers that are the sum of 2 successive evil numbers (A001969).

%C First differences are in {3, 4, 5}; 4*n - 2 <= a(n) <= 4*n. - _Charles R Greathouse IV_, Dec 26 2013

%H Amiram Eldar, <a href="/A234431/b234431.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A001969(n) + A001969(n + 1).

%t Total/@Partition[Select[Range[0,200],EvenQ[DigitCount[#,2,1]]&],2,1] (* _Harvey P. Dale_, Nov 02 2015 *)

%o (PARI) a(n)=4*n+hammingweight(n-1)%2+hammingweight(n)%2-2 \\ _Charles R Greathouse IV_, Dec 26 2013

%Y Cf. A001969, A003159 (indices of odd numbers in A234431), A131323 (odd numbers in A234431).

%K nonn,easy,base

%O 1,1

%A _Irina Gerasimova_, Dec 26 2013

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Last modified May 7 20:36 EDT 2021. Contains 343652 sequences. (Running on oeis4.)