cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 93 results. Next

A024318 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = (Fibonacci numbers).

Original entry on oeis.org

0, 0, 1, 2, 3, 5, 8, 13, 26, 42, 68, 110, 178, 288, 466, 754, 1254, 2029, 3283, 5312, 8595, 13907, 22502, 36409, 58911, 95320, 154608, 250161, 404769, 654930, 1059699, 1714629, 2774328, 4488957, 7263285
Offset: 1

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Programs

  • Magma
    b:= func< n,j | IsIntegral((Sqrt(8*j+9) -3)/2) select Fibonacci(n-j+1) else 0 >;
    A024318:= func< n | (&+[b(n,j): j in [1..Floor((n+1)/2)]]) >;
    [A024318(n) : n in [1..80]]; // G. C. Greubel, Jan 19 2022
    
  • Mathematica
    Table[t=0; m=3; p=BitShiftRight[n]; n--; While[n>p, t += Fibonacci[n+1]; n -= m++]; t, {n, 120}] (* G. C. Greubel, Jan 19 2022 *)
  • Sage
    def b(n,j): return fibonacci(n-j+1) if ((sqrt(8*j+9) -3)/2).is_integer() else 0
    def A024318(n): return sum( b(n,j) for j in (1..floor((n+1)/2)) )
    [A024318(n) for n in (1..120)] # G. C. Greubel, Jan 19 2022

Formula

a(n) = Sum_{j=1..floor((n+1)/2)} A023531(j)*Fibonacci(n-j+1). - G. C. Greubel, Jan 19 2022

A024316 a(n) = s(1)*s(n) + s(2)*s(n-1) + ... + s(k)*s(n+1-k), where k = floor((n+1)/2), s = A023531.

Original entry on oeis.org

0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 2, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 2, 1, 0, 0, 1, 0, 1, 1, 0, 2, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 2, 1, 0, 0, 2, 0, 0, 0, 0, 3, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1
Offset: 1

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Programs

  • Haskell
    a024316 n = sum $ take (div (n + 1) 2) $ zipWith (*) zs $ reverse zs
                where zs = take n $ tail a023531_list
    -- Reinhard Zumkeller, Feb 14 2015
    
  • Magma
    A023531:= func< n | IsIntegral( (Sqrt(8*n+9) - 3)/2 ) select 1 else 0 >;
    [ (&+[A023531(j)*A023531(n-j+1): j in [1..Floor((n+1)/2)]]) : n in [1..110]]; // G. C. Greubel, Jan 17 2022
    
  • Mathematica
    A023531[n_]:= SquaresR[1, 8n+9]/2;
    a[n_]:= a[n]= Sum[A023531[j]*A023531[n-j+1], {j, Floor[(n+1)/2]}];
    Table[a[n], {n, 110}] (* G. C. Greubel, Jan 17 2022 *)
  • Sage
    def A023531(n):
        if ((sqrt(8*n+9) -3)/2).is_integer(): return 1
        else: return 0
    [sum( A023531(j)*A023531(n-j+1) for j in (1..floor((n+1)/2)) ) for n in (1..110)] # G. C. Greubel, Jan 17 2022

Formula

a(n) = Sum_{j=1..floor((n+1)/2)} A023531(j)*A023531(n-j+1). - G. C. Greubel, Jan 17 2022

A024317 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = A023532.

Original entry on oeis.org

0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 2, 2, 1, 2, 1, 2, 2, 2, 3, 3, 2, 2, 3, 2, 3, 3, 3, 2, 4, 4, 3, 4, 3, 4, 3, 3, 4, 4, 3, 4, 5, 5, 4, 5, 4, 4, 5, 3, 5, 5, 5, 4, 5, 5, 5, 6, 5, 5, 6, 6, 5, 5, 5, 6, 6, 5, 5, 6, 5, 6, 7, 7, 5, 7, 7, 7, 7, 4, 7, 6, 6, 7, 7, 6, 6, 7, 7, 7, 8, 7, 6, 8, 8, 7, 8, 7, 7, 7, 7, 8, 8, 8, 6, 8, 7, 8, 8, 7, 8, 9, 8, 8
Offset: 1

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Programs

  • Magma
    A023531:= func< n | IsIntegral( (Sqrt(8*n+9) -3)/2 ) select 1 else 0 >;
    [ (&+[A023531(j)*(1 - A023531(n-j+1)): j in [1..Floor((n+1)/2)]]) : n in [1..90]]; // G. C. Greubel, Jan 19 2022
    
  • Mathematica
    A023531[n_]:= SquaresR[1, 8n+9]/2;
    a[n_]:= Sum[A023531[j]*(1 - A023531[n-j+1]), {j, Floor[(n+1)/2]}];
    Table[a[n], {n, 90}] (* G. C. Greubel, Jan 19 2022 *)
  • Sage
    def A023531(n):
        if ((sqrt(8*n+9) -3)/2).is_integer(): return 1
        else: return 0
    [sum( A023531(j)*(1-A023531(n-j+1)) for j in (1..floor((n+1)/2)) ) for n in (1..90)] # G. C. Greubel, Jan 19 2022

Formula

a(n) = Sum_{k=1..floor((n+1)/2)} A023531(k)*A023532(n-k+1). - G. C. Greubel, Jan 19 2022

A024313 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = (natural numbers >= 3), t = A023531.

Original entry on oeis.org

3, 3, 10, 17, 37, 59, 114, 185, 334, 540, 938, 1518, 2573, 4163, 6946, 11239, 18559, 30029, 49248, 79685, 130090, 210490, 342596, 554332, 900423, 1456915, 2363370, 3824013, 6197753
Offset: 1

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Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 40);
    Coefficients(R!( x*(3-2*x^2+4*x^3-x^4-3*x^5-2*x^7)/((1-x-x^2)*(1-x^2-x^4)^2) )); // G. C. Greubel, Jan 17 2022
    
  • Mathematica
    a[n_]:= With[{F=Fibonacci}, If[EvenQ[n], LucasL[n+3] + F[n+2] - LucasL[n/2 +3] - (n/2 +1)*F[n/2 +2], LucasL[n+3] + F[n+2] - LucasL[(n+5)/2]-(n+3)/2*Fibonacci[(n+3)/2]]];
    Table[a[n], {n, 40}] (* G. C. Greubel, Jan 17 2022 *)
  • Sage
    def A024313_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x*(3 -2*x^2 +4*x^3 -x^4 -3*x^5 -2*x^7)/((1-x-x^2)*(1-x^2-x^4)^2) ).list()
    a=A024313_list(41); a[1:] # G. C. Greubel, Jan 17 2022

Formula

G.f.: x*(3-2*x^2+4*x^3-x^4-3*x^5-2*x^7)/((1-x-x^2)*(1-x^2-x^4)^2). - Maksym Voznyy (voznyy(AT)mail.ru), Jul 27 2009
From G. C. Greubel, Jan 17 2022: (Start)
a(2*n) = Lucas(2*n+3) + F(2*n+2) - Lucas(n+3) - (n+1)*F(n+2).
a(2*n+1) = Lucas(2*n+4) + F(2*n+3) - Lucas(n+3) - (n+2)*F(n+2), where F(n) = A000045(n). (End)

A024319 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = (Lucas numbers).

Original entry on oeis.org

0, 0, 3, 4, 7, 11, 18, 29, 58, 94, 152, 246, 398, 644, 1042, 1686, 2804, 4537, 7341, 11878, 19219, 31097, 50316, 81413, 131729, 213142, 345714, 559377, 905091, 1464468, 2369559, 3834027, 6203586
Offset: 1

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Programs

  • Magma
    A023531:= func< n | IsIntegral( (Sqrt(8*n+9) -3)/2 ) select 1 else 0 >;
    [ (&+[A023531(j)*Lucas(n-j+1): j in [1..Floor((n+1)/2)]]) : n in [1..40]]; // G. C. Greubel, Jan 19 2022
    
  • Mathematica
    A023531[n_]:= SquaresR[1, 8n+9]/2;
    a[n_]:= Sum[A023531[j]*LucasL[n-j+1], {j, Floor[(n+1)/2]}];
    Table[a[n], {n, 40}] (* G. C. Greubel, Jan 19 2022 *)
  • Sage
    def A023531(n):
        if ((sqrt(8*n+9) -3)/2).is_integer(): return 1
        else: return 0
    [sum( A023531(j)*lucas_number2(n-j+1,1,-1) for j in (1..floor((n+1)/2)) ) for n in (1..40)] # G. C. Greubel, Jan 19 2022

Formula

a(n) = Sum_{j=1..floor((n+1)/2)} A023531(j)*Lucas(n-j+1). - G. C. Greubel, Jan 19 2022

A024320 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = (1, p(1), p(2), ... ).

Original entry on oeis.org

0, 0, 2, 3, 5, 7, 11, 13, 24, 30, 36, 46, 50, 60, 70, 74, 103, 117, 131, 139, 157, 171, 177, 193, 207, 221, 278, 294, 310, 330, 348, 360, 390, 408, 424, 448, 470, 486, 573, 611, 625, 653, 673, 699, 739, 761, 781, 803, 835, 863, 891, 925, 1054, 1078, 1104, 1136, 1180, 1214
Offset: 1

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Programs

  • Magma
    A023531:= func< n | IsIntegral( (Sqrt(8*n+9) -3)/2 ) select 1 else 0 >;
    p:= func< n | n eq 1 select 1 else NthPrime(n-1) >;
    [ (&+[A023531(j)*p(n-j+1): j in [1..Floor((n+1)/2)]]) : n in [1..60]]; // G. C. Greubel, Jan 19 2022
    
  • Mathematica
    A023531[n_]:= SquaresR[1, 8*n+9]/2;
    p[n_]:= If[n==1, 1, Prime[n-1]];
    a[n_]:= Sum[A023531[j]*p[n-j+1], {j, Floor[(n+1)/2]}];
    Table[a[n], {n, 60}] (* G. C. Greubel, Jan 19 2022 *)
  • Sage
    def A023531(n):
        if ((sqrt(8*n+9) -3)/2).is_integer(): return 1
        else: return 0
    def p(n):
        if (n==1): return 1
        else: return nth_prime(n-1)
    [sum( A023531(j)*p(n-j+1) for j in (1..floor((n+1)/2)) ) for n in (1..60)] # G. C. Greubel, Jan 19 2022

Formula

a(n) = A023531(1) + Sum_{j=2..floor((n+1)/2)} A023531(j)*Prime(n-j+1). - G. C. Greubel, Jan 19 2022

A024321 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = (composite numbers).

Original entry on oeis.org

0, 0, 6, 8, 9, 10, 12, 14, 25, 28, 32, 35, 37, 40, 44, 46, 64, 69, 73, 77, 81, 85, 89, 93, 96, 100, 128, 133, 139, 144, 148, 154, 162, 166, 170, 176, 181, 187, 223, 229, 236, 242, 248, 255, 262, 268, 275, 281, 287, 294, 301, 308, 354, 361, 370, 380, 386, 394, 401, 408, 418, 425
Offset: 1

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Programs

  • Magma
    A002808:= [n : n in [2..100] | not IsPrime(n) ];
    A023531:= func< n | IsIntegral( (Sqrt(8*n+9) -3)/2 ) select 1 else 0 >;
    [ (&+[A023531(j)*A002808[n-j+1]: j in [1..Floor((n+1)/2)]]) : n in [1..70]]; // G. C. Greubel, Jan 19 2022
    
  • Mathematica
    A023531[n_]:= SquaresR[1, 8n+9]/2;
    Composite[n_]:= FixedPoint[n +PrimePi[#] +1 &, n];
    a[n_]:= Sum[A023531[j]*Composite[n-j+1], {j, Floor[(n+1)/2]}];
    Table[a[n], {n, 70}] (* G. C. Greubel, Jan 19 2022 *)
  • Sage
    A002808 = [n for n in (1..250) if sloane.A001222(n) > 1]
    def A023531(n):
        if ((sqrt(8*n+9) -3)/2).is_integer(): return 1
        else: return 0
    [sum( A023531(j)*A002808[n-j] for j in (1..floor((n+1)/2)) ) for n in (1..70)] # G. C. Greubel, Jan 19 2022

Formula

a(n) = Sum_{j=1..floor((n+1)/2)} A023531(j)*A002808(n-j+1). - G. C. Greubel, Jan 19 2022

A024322 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = (F(2), F(3), ...).

Original entry on oeis.org

0, 0, 2, 3, 5, 8, 13, 21, 42, 68, 110, 178, 288, 466, 754, 1220, 2029, 3283, 5312, 8595, 13907, 22502, 36409, 58911, 95320, 154231, 250161, 404769, 654930, 1059699, 1714629, 2774328, 4488957, 7263285
Offset: 1

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Programs

  • Magma
    A023531:= func< n | IsIntegral( (Sqrt(8*n+9) - 3)/2 ) select 1 else 0 >;
    [ (&+[A023531(j)*Fibonacci(n-j+2): j in [1..Floor((n+1)/2)]]) : n in [1..40]]; // G. C. Greubel, Jan 20 2022
    
  • Mathematica
    A010054[n_]:= SquaresR[1, 8n+1]/2;
    a[n_]:= Sum[A010054[j+1]*Fibonacci[n-j+2], {j, Floor[(n+1)/2]}];
    Table[a[n], {n, 40}] (* G. C. Greubel, Jan 20 2022 *)
  • Sage
    def A023531(n):
        if ((sqrt(8*n+9) -3)/2).is_integer(): return 1
        else: return 0
    [sum( A023531(j)*fibonacci(n-j+2) for j in (1..floor((n+1)/2)) ) for n in (1..40)] # G. C. Greubel, Jan 20 2022

Formula

From G. C. Greubel, Jan 20 2022: (Start)
a(n) = Sum_{j=1..floor((n+1)/2)} A023531(j)*A000045(n-j+1).
a(n) = Sum_{j=1..floor((n+1)/2)} A010054(j+1)*A000045(n-j+2). (End)

A024323 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = (odd natural numbers).

Original entry on oeis.org

0, 0, 3, 5, 7, 9, 11, 13, 24, 28, 32, 36, 40, 44, 48, 52, 73, 79, 85, 91, 97, 103, 109, 115, 121, 127, 160, 168, 176, 184, 192, 200, 208, 216, 224, 232, 240, 248, 295, 305, 315, 325, 335, 345, 355, 365, 375, 385, 395, 405, 415, 425, 488, 500, 512, 524, 536, 548, 560, 572, 584
Offset: 1

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Programs

  • Magma
    A023531:= func< n | IsIntegral( (Sqrt(8*n+9) - 3)/2 ) select 1 else 0 >;
    [ (&+[A023531(j)*(2*n-2*j+1): j in [1..Floor((n+1)/2)]]) : n in [1..70]]; // G. C. Greubel, Jan 20 2022
    
  • Mathematica
    A023531[n_]:= SquaresR[1, 8n+9]/2;
    a[n_]:= Sum[A023531[j]*(2*n-2*j+1), {j, Floor[(n+1)/2]}];
    Table[a[n], {n, 70}] (* G. C. Greubel, Jan 20 2022 *)
  • Sage
    def A023531(n):
        if ((sqrt(8*n+9) -3)/2).is_integer(): return 1
        else: return 0
    [sum( A023531(j)*(2*n-2*j+1) for j in (1..floor((n+1)/2)) ) for n in (1..70)] # G. C. Greubel, Jan 20 2022

Formula

a(n) = Sum_{j=1..floor((n+1)/2)} A023531(j)*(2*n -2*j + 1). - G. C. Greubel, Jan 20 2022

A024324 a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = A000201 (lower Wythoff sequence).

Original entry on oeis.org

0, 0, 3, 4, 6, 8, 9, 11, 20, 23, 27, 29, 33, 37, 39, 43, 60, 65, 70, 74, 80, 84, 89, 94, 98, 104, 131, 137, 143, 150, 157, 163, 169, 176, 183, 189, 195, 202, 241, 248, 256, 265, 272, 281, 289, 296, 306, 313, 321, 329, 337, 346, 397, 406, 416, 425, 436, 445, 454, 466, 474, 484
Offset: 1

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Author

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Crossrefs

Programs

  • Magma
    b:= func< n,j | IsIntegral((Sqrt(8*j+9) -3)/2) select Fibonacci(n-j+1) else 0 >;
    A024324:= func< n | (&+[b(n,j): j in [1..Floor((n+1)/2)]]) >;
    [A024324(n) : n in [1..80]]; // G. C. Greubel, Jan 28 2022
    
  • Mathematica
    Table[t=0; m=3; p=BitShiftRight[n]; n--; While[n>p, t += Floor[n*GoldenRatio^2]; n -= m++]; t, {n, 120}] (* G. C. Greubel, Jan 28 2022 *)
  • PARI
    my(phi=quadgen(5)); a(n) = my(L=n>>1,m=2,ret=0); n--; while(n>L, ret += floor(n*phi); n-=(m++)); ret; \\ Kevin Ryde, Feb 03 2022
  • Sage
    def b(n,j): return floor( (n+1-j)*(1+sqrt(5))/2 ) if ((sqrt(8*j+9) -3)/2).is_integer() else 0
    def A024324(n): return sum( b(n,k) for k in (1..((n+1)//2)) )
    [A024324(n) for n in (1..80)] # G. C. Greubel, Jan 28 2022
    

Formula

a(n) = Sum_{j=1..floor((n+1)/2)} A023531(j)*A000201(n-j+1).

Extensions

a(62) corrected by Sean A. Irvine, Jun 27 2019
Showing 1-10 of 93 results. Next