A079523 -id:A079523 - cp's OEIS frontend

A231271 Numbers k such that k and k+d are both odious (A000069) or both evil (A001969) for every divisor d of k.

1, 5, 7, 9, 13, 17, 23, 29, 31, 37, 41, 49, 53, 61, 71, 73, 85, 89, 97, 101, 103, 109, 113, 119, 125, 127, 129, 133, 137, 149, 151, 157, 167, 173, 181, 193, 197, 199, 217, 223, 229, 233, 241, 249, 257, 263, 269, 277, 281, 293, 311, 313, 317, 321, 325, 337, 341

Offset: 1

Vladimir Shevelev, Nov 06 2013

A prime p is a term iff its binary expansion ends in odd number of 1's (A095283). All terms are in A079523.

			The odious number k = 341 has divisors {1, 11, 31, 341}. Since the numbers 341 + 1 = 342, 341 + 11 = 352, 341 + 31 = 372, 341 + 341 = 682 are all odious, then 341 is a term.

Peter J. C. Moses, Table of n, a(n) for n = 1..10000

Cf. A000069, A001969, A079523, A095283.

odiousQ[n_] := OddQ[DigitCount[n, 2][[1]]];selQ[n_] := Length[Union[Map[odiousQ, Flatten[{n, Map[n+#&, Divisors[n]]}]]]] == 1; Select[Range[200], selQ] (* Peter J. C. Moses, Nov 08 2013 *)

is(k) = {my(hw = hammingweight(k) % 2); fordiv(k, d, if(hammingweight(k+d) % 2 != hw, return(0))); 1;} \\ Amiram Eldar, Aug 12 2024

More terms from Peter J. C. Moses, Nov 08 2013

A231558 Odd composite numbers n, such that n, n+d, n*d and n/d are all odious (A000069) for every divisor d of n.

Original entry on oeis.org

217, 511, 889, 949, 1957, 2041, 2263, 2413, 2869, 3113, 3133, 3481, 3991, 5201, 5761, 7813, 7903, 8071, 8137, 8773, 10519, 10609, 11377, 11879, 12191, 12313, 12871, 15127, 15223, 16177, 19561, 19733, 19879, 21151, 23077, 23233, 23449, 23573, 26221, 27469

Offset: 1

Vladimir Shevelev and Peter J. C. Moses, Nov 11 2013

All terms are in A079523.

			Let n=217. Its divisors are {1,7,31,217}. We see that all numbers 217+1=218, 217+7=224, 217+31=248, 217+217=434, 217/1=217, 217/7=31, 217/31=7, 217/217=1, 217*1=217, 217*7=1519, 217*31=6727, 217*217=47089 are odious. Thus 217 is in the sequence.

Peter J. C. Moses, Table of n, a(n) for n = 1..10000

Cf. A231271, A228436, A000069, A079523.

A332447 a(n) = A007814(A087808(n)).

Original entry on oeis.org

0, 1, 1, 2, 0, 2, 0, 3, 0, 1, 2, 3, 0, 1, 2, 4, 0, 1, 1, 2, 0, 3, 0, 4, 0, 1, 1, 2, 0, 3, 0, 5, 0, 1, 1, 2, 0, 2, 0, 3, 0, 1, 3, 4, 0, 1, 1, 5, 0, 1, 1, 2, 0, 2, 0, 3, 0, 1, 3, 4, 0, 1, 1, 6, 0, 1, 1, 2, 0, 2, 0, 3, 0, 1, 2, 3, 0, 1, 3, 4, 0, 1, 1, 2, 0, 4, 0, 5, 0, 1, 1, 2, 0, 2, 0, 6, 0, 1, 1, 2, 0, 2, 0, 3, 0

Offset: 1

Antti Karttunen, Feb 14 2020

nonn

Antti Karttunen, Table of n, a(n) for n = 1..65537
Index entries for sequences related to binary expansion of n

Cf. A007814, A087808, A332448.

Cf. A000079 (positions of records), A079523 (of zeros).

A087808(n) = if(n<1, 0, if(n%2==0, 2*A087808(n/2), A087808((n-1)/2)+1));
A332447(n) = valuation(A087808(n),2);

a(n) = A007814(A087808(n)).

For n >= 0, a(2^n) = n. [These are the first occurrences of each n]

A162311 Numbers such that A010060(n) = A010060(n+7).

Original entry on oeis.org

1, 3, 4, 5, 7, 10, 14, 17, 19, 20, 21, 23, 25, 27, 28, 29, 31, 33, 35, 36, 37, 39, 42, 46, 49, 51, 52, 53, 55, 58, 62

Offset: 1

Vladimir Shevelev, Jul 01 2009

Or union of intersection of A161673 and {A121539(n)-7} and intersection of A161639 and {A079523(n)-7}.

Conjecture: In every sequence of numbers n, such that A010060(n)=A010060(n+k), for fixed odd k, the odious (A000069) and evil (A001969) terms alternate. - Vladimir Shevelev, Jul 31 2009

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
J.-P. Allouche, Thue, Combinatorics on words, and conjectures inspired by the Thue-Morse sequence, arXiv:1401.3727 [math.NT], 2014.
J.-P. Allouche, Thue, Combinatorics on words, and conjectures inspired by the Thue-Morse sequence, J. de Théorie des Nombres de Bordeaux, 27, no. 2 (2015), 375-388.
V. Shevelev, Equations of the form t(x+a)=t(x) and t(x+a)=1-t(x) for Thue-Morse sequence, arXiv:0907.0880 [math.NT], 2009-2012.

Cf. A161890, A161824, A161817, A161674, A161673, A161639, A161641, A161627, A161579, A161580, A121539, A131323, A036554, A010060, A079523, A081706, A161916, A161974.

tm[0] = 0; tm[n_?EvenQ] := tm[n] = tm[n/2]; tm[n_] := tm[n] = 1 - tm[(n - 1)/2]; Reap[For[n = 0, n <= 20000, n++, If[tm[n] == tm[n + 7], Sow[n]]]][[2, 1]] (* G. C. Greubel, Jan 05 2018 *)

is(n)=hammingweight(n)%2==hammingweight(n+7)%2 \\ Charles R Greathouse IV, Aug 20 2013

A162648 Locations of patterns 1001 or 0110 in the Thue-Morse sequence A010060.

Original entry on oeis.org

0, 4, 6, 8, 12, 16, 20, 22, 24, 28, 30, 32, 36, 38, 40, 44, 48, 52, 54, 56, 60, 64, 68, 70, 72, 76, 80, 84, 86, 88, 92, 94, 96, 100, 102, 104, 108, 112, 116, 118, 120, 124, 126, 128, 132, 134, 136, 140, 144, 148, 150, 152, 156, 158, 160, 164, 166, 168, 172, 176, 180

Offset: 1

Vladimir Shevelev, Jul 08 2009

nonn

Numbers n for which A010060(n+1) = A010060(n+2) = 1-A010060(n) and A010060(n+3) = A010060(n).

Or intersection of A121539, A161674, and A161579.

G. C. Greubel, Table of n, a(n) for n = 1..10000

Cf. A161824, A161817, A161674, A161673, A161639, A161641, A161627, A161579, A161580, A121539, A131323, A036554, A010060, A079523, A081706.

Select[Range[3500], MatchQ[IntegerDigits[#, 2], {b : (1) ..} | {_, 0, b : (1) ..} /; OddQ[Length[{b}]]] &] - 1 (* G. C. Greubel, Jan 05 2018 *)
With[{nn=200},Sort[Join[SequencePosition[ThueMorse[Range[0,nn]],{1,0,0,1}],SequencePosition[ ThueMorse[Range[0,nn]],{0,1,1,0}]]][[;;,1]]]-1 (* Harvey P. Dale, Aug 20 2024 *)

is(n)=my(v=vector(4,i,hammingweight(n+i-1))); v[1]==v[4] && v[1]!=v[2] && v[1]!=v[3] \\ Charles R Greathouse IV, Aug 20 2013

a(n) = A079523(n) - 1.

More readable definition from R. J. Mathar, Sep 16 2009

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

A231271 Numbers k such that k and k+d are both odious (A000069) or both evil (A001969) for every divisor d of k.

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A231558 Odd composite numbers n, such that n, n+d, n*d and n/d are all odious (A000069) for every divisor d of n.

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A332447 a(n) = A007814(A087808(n)).

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A162311 Numbers such that A010060(n) = A010060(n+7).

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A162648 Locations of patterns 1001 or 0110 in the Thue-Morse sequence A010060.

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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).

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