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

3, 8, 11, 15, 19, 22, 27, 32, 35, 38, 43, 47, 51, 56, 59, 63, 67, 70, 75, 79, 83, 88, 91, 94, 99, 104, 107, 111, 115, 118, 123, 128, 131, 134, 139, 143, 147, 152, 155, 158, 163, 168, 171, 175, 179, 182, 187, 191, 195, 200, 203, 207, 211, 214, 219, 224, 227, 230, 235, 239, 243, 248, 251

Offset: 1

Author

Irina Gerasimova, Dec 26 2013

Keywords

• nonn
• easy
• base

Comments

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

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

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

Programs

Mathematica

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

PARI

a(n)=4*n+hammingweight(n-1)%2+hammingweight(n)%2-2 \\ Charles R Greathouse IV, Dec 26 2013

Formula

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