A131323 -id:A131323 - cp's OEIS frontend

A234648 Even sums of 2 consecutive odious numbers (A000069).

6, 24, 30, 40, 54, 72, 86, 96, 102, 120, 126, 136, 150, 160, 166, 184, 198, 216, 222, 232, 246, 264, 278, 288, 294, 312, 326, 344, 350, 360, 374, 384, 390, 408, 414, 424, 438, 456, 470, 480, 486, 504, 510, 520, 534, 544, 550, 568, 582, 600, 606, 616, 630

Offset: 1

Gerasimov Sergey, Dec 29 2013

All the terms in this sequence are evil numbers (A001969).

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

Intersection of A005843 and A234011.

Cf. A000069, A001969, A036554, A131323, A225822.

odQ[n_] := OddQ @ DigitCount[n, 2, 1]; Select[Plus @@@ Partition[Select[ Range[320], odQ], 2, 1], EvenQ] (* Amiram Eldar, Aug 31 2020 *)

a(n) = A234011(A036554(n)) = A225822(n) + (-1)^n.

A386987 For n >= 2, a(n) is the least r >= 1 such that T(n - r) + ... + T(n - 1) = T(n + 1) + ... + T(n + r) where T(i) is A010060(i).

Original entry on oeis.org

2, 1, 1, 2, 4, 3, 3, 4, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 4, 3, 3, 4, 2, 1, 1, 2, 4, 3, 3, 4, 2, 1, 1, 2, 4, 3, 3, 4, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 4, 3, 3, 4, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 4, 3, 3, 4, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 4, 3, 3

Offset: 2

Ctibor O. Zizka, Aug 12 2025

nonn

a(n) is from {1, 2, 3, 4}.

			For n = 6: T(6 - r) + ... + T(5) = T(7) + ... + T(6 + r) is true for the least r = 4  because A010060(2) + A010060(3) + A010060(4) + A010060(5) = A010060(7) + A010060(8) + A010060(9) + A010060(10), thus a(6) = 4.

Cf. A010060, A056196, A079523, A081706, A131323, A225822, A249034.

a[n_] := Module[{s = 0, r = 1}, While[r <= n && (r == 1 || s != 0), s += (ThueMorse[n - r] - ThueMorse[n + r]); r++]; r-1]; Array[a, 100, 2] (* Amiram Eldar, Aug 12 2025 *)

a(A081706(n) + 1) = 1.
a(2*A079523(n)) = 2.
a(A249034(n))= 2.
a(A225822(n)) = 3.
a(A056196(n)) = 3.
a(2*A131323(n)) = 4.
a(2*A249034(n) - 1) = 4.

cp's OEIS Frontend

A234648 Even sums of 2 consecutive odious numbers (A000069).

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