A035513 Wythoff array read by falling antidiagonals.
1, 2, 4, 3, 7, 6, 5, 11, 10, 9, 8, 18, 16, 15, 12, 13, 29, 26, 24, 20, 14, 21, 47, 42, 39, 32, 23, 17, 34, 76, 68, 63, 52, 37, 28, 19, 55, 123, 110, 102, 84, 60, 45, 31, 22, 89, 199, 178, 165, 136, 97, 73, 50, 36, 25, 144, 322, 288, 267, 220, 157, 118, 81, 58, 41, 27, 233, 521
Offset: 1
A127830 a(n) = Sum_{k=0..n} (binomial(floor(k/2),n-k) mod 2).
1, 1, 1, 2, 2, 1, 2, 3, 3, 3, 2, 2, 3, 2, 3, 5, 5, 4, 4, 5, 4, 3, 3, 3, 4, 4, 3, 4, 5, 3, 5, 8, 8, 7, 6, 7, 7, 5, 6, 8, 7, 6, 5, 5, 5, 4, 4, 5, 6, 5, 5, 7, 6, 4, 5, 6, 7, 7, 5, 6, 8, 5, 8, 13, 13, 11, 10, 12, 11, 8, 9, 11, 11, 10, 8, 9, 10, 7, 9, 13, 12
Offset: 0
Comments
Row sums of number triangle A127829.
From Johannes W. Meijer, Jun 05 2011: (Start)
The Ze3 and Ze4 triangle sums, see A180662 for their definitions, of Sierpinski's triangle A047999 equal this sequence.
The sequences A127830(2^n-p), p>=0, are apparently all Fibonacci like sequences, i.e., the next term is the sum of the two nonzero terms that precede it; see the crossrefs. (End)
Crossrefs
Cf.: A000045 (p=0), A000204 (p=7), A001060 (p=13), A000285 (p=14), A022095 (p=16), A022120 (p=24), A022121 (p=25), A022113 (p=28), A022096 (p=30), A022097 (p=31), A022098 (p=32), A022130 (p=44), A022137 (p=48), A022138 (p=49), A022122 (p=52), A022114 (p=53), A022123 (p=56), A022115 (p=60), A022100 (p=62), A022101 (p=63), A022103 (p=64), A022136 (p=79), A022388 (p=80), A022389 (p=88). - Johannes W. Meijer, Jun 05 2011
Programs
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Maple
A127830 := proc(n) local k: option remember: add(binomial(floor(k/2), n-k) mod 2, k=0..n) end: seq(A127830(n), n=0..80); # Johannes W. Meijer, Jun 05 2011
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Mathematica
Table[Sum[Mod[Binomial[Floor[k/2],n-k],2],{k,0,n}],{n,0,80}] (* James C. McMahon, Jan 04 2025 *)
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Python
def A127830(n): return sum(not ~(k>>1)&n-k for k in range(n+1)) # Chai Wah Wu, Jul 29 2025
A192752 Constant term of the reduction by x^2->x+1 of the polynomial p(n,x) defined below in Comments.
1, 7, 12, 23, 39, 66, 109, 179, 292, 475, 771, 1250, 2025, 3279, 5308, 8591, 13903, 22498, 36405, 58907, 95316, 154227, 249547, 403778, 653329, 1057111, 1710444, 2767559, 4478007, 7245570, 11723581, 18969155, 30692740, 49661899, 80354643
Offset: 0
Keywords
Comments
Programs
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Mathematica
q = x^2; s = x + 1; z = 40; p[0, n_] := 1; p[n_, x_] := x*p[n - 1, x] + 4 n + 3; Table[Expand[p[n, x]], {n, 0, 7}] reduce[{p1_, q_, s_, x_}] := FixedPoint[(s PolynomialQuotient @@ #1 + PolynomialRemainder @@ #1 &)[{#1, q, x}] &, p1] t = Table[reduce[{p[n, x], q, s, x}], {n, 0, z}]; u1 = Table[Coefficient[Part[t, n], x, 0], {n, 1, z}](* A192752 *) u2 = Table[Coefficient[Part[t, n], x, 1], {n, 1, z}](* A192753 *)
Formula
Conjecture: G.f.: ( 1+5*x-2*x^2 ) / ( (x-1)*(x^2+x-1) ). a(n) = A000071(n+3)+5*A000071(n+2) -2*A000071(n+1) and first differences in A022136. - R. J. Mathar, May 04 2014
A098127 Fibonacci sequence with a(1) = 7 and a(2) = 26.
7, 26, 33, 59, 92, 151, 243, 394, 637, 1031, 1668, 2699, 4367, 7066, 11433, 18499, 29932, 48431, 78363, 126794, 205157, 331951, 537108, 869059, 1406167, 2275226, 3681393, 5956619, 9638012, 15594631, 25232643, 40827274, 66059917, 106887191, 172947108
Offset: 1
Keywords
Examples
a(3) = a(2) + a(1) = 26 + 7 = 33.
Links
- Tanya Khovanova, Recursive Sequences
- Index entries for linear recurrences with constant coefficients, signature (1, 1).
Programs
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Maple
a[1]:=7:a[2]:=26: for n from 3 to 37 do a[n]:=a[n-1]+a[n-2] od: seq(a[n],n=1..37); # Emeric Deutsch, Apr 16 2005
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Mathematica
LinearRecurrence[{1, 1}, {7, 26}, 80] (* Vladimir Joseph Stephan Orlovsky, Feb 17 2012 *)
Formula
a(n) = a(n-1) + a(n-2).
G.f.: (7x + 19x^2)/(1 - x - x^2). - Emeric Deutsch, Apr 16 2005
Extensions
More terms from Emeric Deutsch, Apr 16 2005
A217762 Square array T, read by antidiagonals: T(n,k) = F(n) + 2*F(k) where F(n) is the n-th Fibonacci number.
0, 2, 1, 2, 3, 1, 4, 3, 3, 2, 6, 5, 3, 4, 3, 10, 7, 5, 4, 5, 5, 16, 11, 7, 6, 5, 7, 8, 26, 17, 11, 8, 7, 7, 10, 13, 42, 27, 17, 12, 9, 9, 10, 15, 21, 68, 43, 27, 18, 13, 11, 12, 15, 23, 34, 110, 69, 43, 28, 19, 15, 14, 17, 23, 36, 55, 178, 111, 69, 44, 29, 21
Offset: 0
Examples
Square array begins: ...0....2....2....4....6...10...16...26...42... ...1....3....3....5....7...11...17...27...43... ...1....3....3....5....7...11...17...27...43... ...2....4....4....6....8...12...18...28...44... ...3....5....5....7....9...13...19...29...45... ...5....7....7....9...11...15...21...31...47... ...8...10...10...12...14...18...24...34...50... ..13...15...15...17...19...23...29...39...55... ..21...23...23...25...27...31...37...47...63... ..34...36...36...38...40...44...50...60...76... ..55...57...57...59...61...65...71...81...97... ..89...91...91...93...95...99..105..115..131... .144..146..146..148..150..154..160..170..186... ...
Crossrefs
Cf. A000045
Formula
T(n,0) = A000045(n).
T(1,k) = A001588(k).
T(n,1) = T(n,2) = A157725(n).
T(n,3) = A157727(n).
T(n+2,n) = A000285(n).
T(n+4,n) = A021120(n).
T(n+6,n) = A022097(n+2).
T(n+7,n) = A022122(n+2).
T(n+8,n) = 3*A013655(n+2).
T(n+9,n) = A097657(n+2).
T(n+10,n) = A022118(n+4).
T(n,n+1) = A000045(n+3).
T(n,n+3) = A000032(n+3).
T(n,n+4) = A022095(n+2).
T(n,n+5) = A022120(n+2).
T(n,n+6) = A022136(n+2).
T(n,n+7) = A022098(n+4).
T(n,n+8) = A022380(n+4).
T(n,n+9) = A206419(n+6).
Sum(T(n-k,k), 0<=k<=n) = 3*A000071(n+2).
Comments
Examples
References
Links
Crossrefs
Programs
Maple
Mathematica
PARI
Python
Python
Formula
Extensions