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

1,1

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

Formula

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

Mathematica

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

Prog

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

Crossrefs

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

Sequence in context: A310281 A287365 A257336 * A310282 A081858 A145837

Adjacent sequences: A234428 A234429 A234430 * A234432 A234433 A234434

Keyword

nonn,easy,base

Author

Irina Gerasimova, Dec 26 2013

Status

approved