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 11 results. Next

A001001 Number of sublattices of index n in generic 3-dimensional lattice.

Original entry on oeis.org

1, 7, 13, 35, 31, 91, 57, 155, 130, 217, 133, 455, 183, 399, 403, 651, 307, 910, 381, 1085, 741, 931, 553, 2015, 806, 1281, 1210, 1995, 871, 2821, 993, 2667, 1729, 2149, 1767, 4550, 1407, 2667, 2379, 4805, 1723, 5187, 1893, 4655, 4030, 3871, 2257, 8463, 2850, 5642, 3991, 6405, 2863
Offset: 1

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Author

Keywords

Comments

These sublattices are in 1-1 correspondence with matrices
[a b d]
[0 c e]
[0 0 f]
with acf = n, b = 0..c-1, d = 0..f-1, e = 0..f-1. The sublattice is primitive if gcd(a,b,c,d,e,f) = 1.
Total area of all distinct rectangles whose side lengths are divisors of n, and whose length is an integer multiple of the width. - Wesley Ivan Hurt, Aug 23 2020

References

  • Richard P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 5.13(d), pp. 76 and 113.

Crossrefs

Column 3 of A160870.
Cf. A060983, A064987 (Mobius transform).
Primes in this sequence are in A053183.

Programs

  • Haskell
    a001001 n = sum [sum [k * (if k `mod` l == 0 then l else 0) | k <- [1..n], n `mod` k == 0 ] | l <- [1..n]]
    a = [ a001001 n | n <- [1..53]]
    putStrLn $ concat $ map (++ ", ") (map show a) -- Miles Wilson, Apr 04 2025
  • Maple
    nmax := 100:
    L12 := [seq(1,i=1..nmax) ];
    L27 := [seq(i,i=1..nmax) ];
    L290 := [seq(i^2,i=1..nmax) ];
    DIRICHLET(L12,L27) ;
    DIRICHLET(%,L290) ; # R. J. Mathar, Sep 25 2017
  • Mathematica
    a[n_] := Sum[ d*DivisorSigma[1, d], {d, Divisors[n]}]; Table[ a[n], {n, 1, 42}] (* Jean-François Alcover, Jan 20 2012, after Vladeta Jovovic *)
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 2}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)
  • PARI
    N=17; default(seriesprecision,N); x=z+O(z^(N+1))
    c=sum(j=1,N,j*x^j);
    t=1/prod(j=1,N, eta(x^(j))^j)
    t=log(t)
    t=serconvol(t,c)
    Vec(t)
    /* Joerg Arndt, May 03 2008 */
    
  • PARI
    a(n)=sumdiv(n,d, d * sumdiv(d,t, t ) );  /* Joerg Arndt, Oct 07 2012 */
    
  • PARI
    a(n)=sumdivmult(n,d, sigma(d)*d) \\ Charles R Greathouse IV, Sep 09 2014
    

Formula

If n = Product p^m, a(n) = Product (p^(m + 1) - 1)(p^(m + 2) - 1)/(p - 1)(p^2 - 1). Or, a(n) = Sum_{d|n} sigma(n/d)*d^2, Dirichlet convolution of A000290 and A000203.
a(n) = Sum_{d|n} d*sigma(d). - Vladeta Jovovic, Apr 06 2001
Multiplicative with a(p^e) = ((p^(e+1)-1)(p^(e+2)-1))/((p-1)(p^2-1)). - David W. Wilson, Sep 01 2001
Dirichlet g.f.: zeta(s)*zeta(s-1)*zeta(s-2).
L.g.f.: -log(Product_{k>=1} (1 - x^k)^sigma(k)) = Sum_{n>=1} a(n)*x^n/n. - Ilya Gutkovskiy, May 23 2018
a(n) = Sum_{d1|n, d2|n, d1|d2} d1*d2. - Wesley Ivan Hurt, Aug 23 2020
Sum_{k=1..n} a(k) ~ c * n^3, where c = Pi^2*zeta(3)/18 = 0.659101... . - Amiram Eldar, Oct 19 2022
G.f.: Sum_{k>=1} Sum {l>=1} k*l^2*x^(k*l - 1)/(1 - x^(k*l)). - Miles Wilson, Apr 04 2025

A160870 Array read by antidiagonals: T(n,k) is the number of sublattices of index n in generic k-dimensional lattice (n >= 1, k >= 1).

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 4, 7, 1, 1, 7, 13, 15, 1, 1, 6, 35, 40, 31, 1, 1, 12, 31, 155, 121, 63, 1, 1, 8, 91, 156, 651, 364, 127, 1, 1, 15, 57, 600, 781, 2667, 1093, 255, 1, 1, 13, 155, 400, 3751, 3906, 10795, 3280, 511, 1, 1, 18, 130, 1395, 2801, 22932, 19531, 43435, 9841, 1023, 1
Offset: 1

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Author

N. J. A. Sloane, Nov 19 2009

Keywords

Examples

			Array begins:
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,...
  1,3,7,15,31,63,127,255,511,1023,2047,4095,8191,16383,32767,65535,...
  1,4,13,40,121,364,1093,3280,9841,29524,88573,265720,797161,2391484,...
  1,7,35,155,651,2667,10795,43435,174251,698027,2794155,11180715,...
  1,6,31,156,781,3906,19531,97656,488281,2441406,12207031,61035156,...
  ...
		

References

  • Günter Scheja, Uwe Storch, Lehrbuch der Algebra, Teil 2. BG Teubner, Stuttgart, 1988. [§63, Aufg. 13]

Crossrefs

Programs

  • Mathematica
    T[, 1] = 1; T[1, ] = 1; T[n_, k_] := T[n, k] = DivisorSum[n, (n/#)^(k-1) *T[#, k-1]&]; Table[T[n-k+1, k], {n, 1, 11}, {k, 1, n}] // Flatten (* Jean-François Alcover, Dec 04 2015 *)
  • PARI
    T(n,k)={ if ( (n==1) || (k==1), 1, sumdiv(n,d, d*T(d, k-1)) ) }

Formula

T(n,1) = 1; T(1,k) = 1; T(n, k) = Sum_{d|n} d*T(d, k-1).
From Álvar Ibeas, Oct 31 2015: (Start)
T(n,k) = Sum_{d|n} (n/d)^(k-1) * T(d, k-1).
T(Product(p^e), k) = Product(Gaussian_poly[e+k-1, e]_p). (End)

A038994 Number of sublattices of index n in generic 7-dimensional lattice.

Original entry on oeis.org

1, 127, 1093, 10795, 19531, 138811, 137257, 788035, 896260, 2480437, 1948717, 11798935, 5229043, 17431639, 21347383, 53743987, 25646167, 113825020, 49659541, 210837145, 150021901, 247487059, 154764793, 861322255, 317886556, 664088461, 678468820, 1481689315
Offset: 1

Views

Author

Keywords

References

  • Michael Baake, "Solution of the coincidence problem in dimensions d <= 4", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44.

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 6}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)

Formula

f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=7.
Multiplicative with a(p^e) = Product_{k=1..6} (p^(e+k)-1)/(p^k-1).
Sum_{k=1..n} a(k) ~ c * n^7, where c = Pi^12*zeta(3)*zeta(5)*zeta(7)/3572100 = 0.325206... . - Amiram Eldar, Oct 19 2022

Extensions

More terms from Amiram Eldar, Aug 29 2019

A038991 Number of sublattices of index n in generic 4-dimensional lattice.

Original entry on oeis.org

1, 15, 40, 155, 156, 600, 400, 1395, 1210, 2340, 1464, 6200, 2380, 6000, 6240, 11811, 5220, 18150, 7240, 24180, 16000, 21960, 12720, 55800, 20306, 35700, 33880, 62000, 25260, 93600, 30784, 97155, 58560, 78300, 62400, 187550, 52060, 108600, 95200, 217620, 70644, 240000, 81400
Offset: 1

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Author

Keywords

References

  • M. Baake, "Solution of coincidence problem...", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44.

Crossrefs

Programs

  • Mathematica
    a[n_] := DivisorSum[n, #*DivisorSum[#, #*DivisorSum[#, #&]&]&]; Array[a, 50] (* Jean-François Alcover, Dec 02 2015, after Joerg Arndt *)
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 3}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)
  • PARI
    a(n)=sumdiv(n,x, x * sumdiv(x,y, y * sumdiv(y,z, z ) ) ); /* Joerg Arndt, Oct 07 2012 */

Formula

f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=4.
Dirichlet g.f.: zeta(s)*zeta(s-1)*zeta(s-2)*zeta(s-3).
Dirichlet convolution of A000578 and A001001.
Multiplicative with a(p^e) = Product_{k=1..3} (p^(e+k)-1)/(p^k-1).
Sum_{k=1..n} a(k) ~ Pi^6 * Zeta(3) * n^4 / 2160. - Vaclav Kotesovec, Feb 01 2019
Conjectured g.f.: Sum_{k>=1} Sum {l>=1} Sum {m>=1} k*l^2*m^3*x^(k*l*m)/(1 - x^(k*l*m)) (by extension of g.f for A001001). - Miles Wilson, Apr 05 2025

Extensions

Offset changed from 0 to 1 by R. J. Mathar, Mar 31 2011
More terms from Joerg Arndt, Oct 07 2012

A038992 Number of sublattices of index n in generic 5-dimensional lattice.

Original entry on oeis.org

1, 31, 121, 651, 781, 3751, 2801, 11811, 11011, 24211, 16105, 78771, 30941, 86831, 94501, 200787, 88741, 341341, 137561, 508431, 338921, 499255, 292561, 1429131, 508431, 959171, 925771, 1823451, 732541, 2929531, 954305, 3309747, 1948705, 2750971, 2187581, 7168161, 1926221
Offset: 1

Views

Author

Keywords

References

  • Michael Baake, "Solution of the coincidence problem in dimensions d <= 4", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44.

Crossrefs

Programs

  • Mathematica
    a[n_] := DivisorSum[n, #*DivisorSum[#, #*DivisorSum[#, #*DivisorSum[#, # &] &] &] &]; Array[a, 50] (* Jean-François Alcover, Dec 02 2015, after Joerg Arndt *)
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 4}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)
  • PARI
    a(n)=sumdiv(n,x, x * sumdiv(x,y, y * sumdiv(y,z, z * sumdiv(z,w, w ) ) ) ); /* Joerg Arndt, Oct 07 2012 */

Formula

f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=5.
Multiplicative with a(p^e) = Product_{k=1..4} (p^(e+k)-1)/(p^k-1).
Dirichlet g.f.: zeta(s)*zeta(s-1)*zeta(s-2)*zeta(s-3)*zeta(s-4). Dirichlet convolution of A038991 with A000583. - R. J. Mathar, Mar 31 2011
Sum_{k=1..n} a(k) ~ c * n^5, where c = Pi^6*zeta(3)*zeta(5)/2700 = 0.443822... . - Amiram Eldar, Oct 19 2022

Extensions

Offset changed from 0 to 1 by R. J. Mathar, Mar 31 2011
More terms from Joerg Arndt, Oct 07 2012

A038995 Number of sublattices of index n in generic 8-dimensional lattice.

Original entry on oeis.org

1, 255, 3280, 43435, 97656, 836400, 960800, 6347715, 8069620, 24902280, 21435888, 142466800, 67977560, 245004000, 320311680, 866251507, 435984840, 2057753100, 943531280, 4241688360, 3151424000, 5466151440, 3559590240, 20820505200, 7947261556, 17334277800, 18326727760
Offset: 1

Views

Author

Keywords

References

  • Michael Baake, "Solution of the coincidence problem in dimensions d <= 4", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44.

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 7}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)

Formula

f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=8.
Multiplicative with a(p^e) = Product_{k=1..7} (p^(e+k)-1)/(p^k-1).
Dirichlet g.f.: Product_{k=0..Q-1} zeta(s-k). - R. J. Mathar, Apr 01 2011
Sum_{k=1..n} a(k) ~ c * n^8, where c = Pi^20*zeta(3)*zeta(5)*zeta(7)/43401015000 = 0.285716... . - Amiram Eldar, Oct 19 2022

Extensions

Offset set to 1 by R. J. Mathar, Mar 01 2011
More terms from Amiram Eldar, Aug 29 2019

A038996 Number of sublattices of index n in generic 9-dimensional lattice.

Original entry on oeis.org

1, 511, 9841, 174251, 488281, 5028751, 6725601, 50955971, 72636421, 249511591, 235794769, 1714804091, 883708281, 3436782111, 4805173321, 13910980083, 7411742281, 37117211131, 17927094321, 85083452531, 66186639441, 120491126959, 81870575521, 501457710611, 198682027181
Offset: 1

Views

Author

Keywords

References

  • Michael Baake, "Solution of the coincidence problem in dimensions d <= 4", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44.

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 8}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)

Formula

f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=9.
Multiplicative with a(p^e) = Product_{k=1..8} (p^(e+k)-1)/(p^k-1).
Dirichlet g.f.: Product_{k=0..Q-1} zeta(s-k). - R. J. Mathar, Apr 01 2011
Sum_{k=1..n} a(k) ~ c * n^9, where c = Pi^20*zeta(3)*zeta(5)*zeta(7)*zeta(9) / 38578680000 = 0.254479... . - Amiram Eldar, Oct 19 2022

Extensions

Offset changed to 1 by R. J. Mathar, Apr 01 2011
More terms from Amiram Eldar, Aug 29 2019

A038997 Number of sublattices of index n in generic 10-dimensional lattice.

Original entry on oeis.org

1, 1023, 29524, 698027, 2441406, 30203052, 47079208, 408345795, 653757313, 2497558338, 2593742460, 20608549148, 11488207654, 48162029784, 72080070744, 222984027123, 125999618778, 668793731199, 340614792100, 1704167305962, 1389966536992, 2653398536580, 1883023236984
Offset: 1

Views

Author

Keywords

References

  • Michael Baake, "Solution of the coincidence problem in dimensions d <= 4", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44.

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 9}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)

Formula

f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=10.
Multiplicative with a(p^e) = Product_{k=1..9} (p^(e+k)-1)/(p^k-1).
Dirichlet g.f.: Product_{k=0..Q-1} zeta(s-k). - R. J. Mathar, Apr 01 2011
Sum_{k=1..n} a(k) ~ c * n^10, where c = Pi^30*zeta(3)*zeta(5)*zeta(7)*zeta(9) / 4511535509250000 = 0.229259... . - Amiram Eldar, Oct 19 2022

Extensions

Offset set to 1 by R. J. Mathar, Apr 01 2011
More terms from Amiram Eldar, Aug 29 2019

A038998 Sublattices of index n in generic 11-dimensional lattice.

Original entry on oeis.org

1, 2047, 88573, 2794155, 12207031, 181308931, 329554457, 3269560515, 5883904390, 24987792457, 28531167061, 247486690815, 149346699503, 674597973479, 1081213356763, 3571013994483, 2141993519227, 12044352286330, 6471681049901, 34108336703805, 29189626919861
Offset: 1

Views

Author

Keywords

References

  • Michael Baake, "Solution of the coincidence problem in dimensions", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44.

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 10}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)

Formula

f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=11.
Multiplicative with a(p^e) = Product_{k=1..10} (p^(e+k)-1)/(p^k-1).
Dirichlet g.f.: Product_{k=0..Q-1} zeta(s-k).
Sum_{k=1..n} a(k) ~ c * n^11, where c = Pi^30*zeta(3)*zeta(5)*zeta(7)*zeta(9)*zeta(11)/4962689060175000 = 0.208520... . - Amiram Eldar, Oct 19 2022

Extensions

Offset set to 1 by R. J. Mathar, Apr 01 2011
More terms from Amiram Eldar, Aug 29 2019

A038999 Sublattices of index n in generic 12-dimensional lattice.

Original entry on oeis.org

1, 4095, 265720, 11180715, 61035156, 1088123400, 2306881200, 26167664835, 52955405230, 249938963820, 313842837672, 2970939589800, 1941507093540, 9446678514000, 16218261652320, 57162391576563, 36413889826860, 216852384416850, 122961939948120, 682416684216540
Offset: 1

Views

Author

Keywords

References

  • Michael Baake, "Solution of the coincidence problem in dimensions d <= 4", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44.

Crossrefs

Programs

  • Mathematica
    f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 11}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *)

Formula

f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=12.
Multiplicative with a(p^e) = Product_{k=1..11} (p^(e+k)-1)/(p^k-1).
Dirichlet g.f.: Product_{k=0..Q-1} zeta(s-k).
Sum_{k=1..n} a(k) ~ c * n^12, where c = Pi^42*zeta(3)*zeta(5)*zeta(7)*zeta(9)*zeta(11)/3456808210410967912500000 = 0.191191... . - Amiram Eldar, Oct 19 2022

Extensions

Offset set to 1 by R. J. Mathar, Apr 01 2011
More terms from Amiram Eldar, Aug 29 2019
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