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.

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A034345 Number of binary [ n,4 ] codes without 0 columns.

Original entry on oeis.org

0, 0, 0, 1, 4, 11, 27, 63, 134, 276, 544, 1048, 1956, 3577, 6395, 11217, 19307, 32685, 54413, 89225, 144144, 229647, 360975, 560259, 858967, 1301757, 1950955, 2893102, 4246868, 6174084, 8892966, 12696295, 17973092, 25237467, 35163431, 48629902, 66774760, 91063984
Offset: 1

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Comments

"We say that the sequence (a_n) is quasi-polynomial in n if there exist polynomials P_0, ..., P_{s-1} and an integer n_0 such that, for all n >= n_0, a_n = P_i(n) where i == n (mod s)." [This is from the abstract of Lisonek (2007), and he states that the condition "n >= n_0" makes his definition broader than the one in Stanley's book. From Section 5 of his paper, we conclude that (a(n): n >= 1) is a quasi-polynomial in n.] - Petros Hadjicostas, Oct 02 2019

Crossrefs

Column k=4 of A034253 and first differences of A034358.

Programs

  • Sage
    # Fripertinger's method to find the g.f. of column k >= 2 of A034253 (for small k):
    def A034253col(k, length):
        G1 = PSL(k, GF(2))
        G2 = PSL(k-1, GF(2))
        D1 = G1.cycle_index()
        D2 = G2.cycle_index()
        f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
        f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
        f = f1 - f2
        return f.taylor(x, 0, length).list()
    # For instance the Taylor expansion for column k = 4 (this sequence) gives
    print(A034253col(4, 30)) #

Extensions

More terms by Petros Hadjicostas, Oct 02 2019

A034346 Number of binary [ n,5 ] codes without 0 columns.

Original entry on oeis.org

0, 0, 0, 0, 1, 5, 17, 54, 163, 465, 1283, 3480, 9256, 24282, 62812, 160106, 401824, 992033, 2406329, 5730955, 13393760, 30709772, 69079030, 152473837, 330344629, 702839150, 1469214076, 3019246455, 6103105779, 12142291541, 23790590387, 45932253637, 87434850942, 164188881007
Offset: 1

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Crossrefs

Column k=5 of A034253 and first differences of A034359.

Programs

  • Sage
    # Fripertinger's method to find the g.f. of column k >= 2 (for small k):
    def A034253col(k, length):
        G1 = PSL(k, GF(2))
        G2 = PSL(k-1, GF(2))
        D1 = G1.cycle_index()
        D2 = G2.cycle_index()
        f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
        f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
        f = f1 - f2
        return f.taylor(x, 0, length).list()
    # For instance the Taylor expansion for column k = 5 gives a(n):
    print(A034253col(5, 30)) # Petros Hadjicostas, Oct 04 2019

Extensions

More terms from Petros Hadjicostas, Oct 04 2019

A034347 Number of binary [ n,6 ] codes without 0 columns.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 6, 25, 99, 385, 1472, 5676, 22101, 87404, 350097, 1413251, 5708158, 22903161, 90699398, 352749035, 1342638839, 4990325414, 18090636016, 63933709870, 220277491298, 740170023052, 2426954735273, 7770739437179, 24314436451415, 74406425640743, 222867051758565, 653898059035166
Offset: 1

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Crossrefs

First differences of A034360.
Column k = 6 of A034253.

Programs

  • SageMath
    # Fripertinger's method to find the g.f. of column k >= 2 of A034253 (for small k):
    def A034253col(k, length):
        G1 = PSL(k, GF(2))
        G2 = PSL(k-1, GF(2))
        D1 = G1.cycle_index()
        D2 = G2.cycle_index()
        f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
        f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
        f = f1 - f2
        return f.taylor(x, 0, length).list()
    # For instance the Taylor expansion for column k = 6 (this sequence) gives
    print(A034253col(6, 30)) # Petros Hadjicostas, Oct 05 2019

Extensions

More terms from Petros Hadjicostas, Oct 05 2019

A034348 Number of binary [ n,7 ] codes without 0 columns.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 7, 35, 170, 847, 4408, 24297, 143270, 901491, 5985278, 41175203, 287813284, 2009864185, 13848061942, 93369988436, 613030637339, 3908996099141, 24179747870890, 145056691643428, 844229016035010, 4769751989333029, 26181645303024760, 139750488576152520
Offset: 1

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Comments

To find the g.f., modify the Sage program below (cf. function f). It is very complicated to write it here. - Petros Hadjicostas, Oct 05 2019

Crossrefs

Column k=7 of A034253 and first differences of A034361.

Programs

  • Sage
    # Fripertinger's method to find the g.f. of column k >= 2 of A034253 (for small k):
    def A034253col(k, length):
        G1 = PSL(k, GF(2))
        G2 = PSL(k-1, GF(2))
        D1 = G1.cycle_index()
        D2 = G2.cycle_index()
        f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
        f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
        f = f1 - f2
        return f.taylor(x, 0, length).list()
    # For instance the Taylor expansion for column k = 7 (this sequence) gives
    print(A034253col(7, 30)) #

Extensions

More terms from Petros Hadjicostas, Oct 05 2019

A034349 Number of binary [ n,8 ] codes without 0 columns.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 8, 47, 277, 1775, 12616, 102445, 957357, 10174566, 119235347, 1482297912, 18884450721, 240477821389, 3012879828566, 36800049400028, 436068618826236, 5001537857507095, 55482177298724426, 595303034603214108, 6181562837200509792, 62170512250565592346
Offset: 1

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Comments

To find the g.f., modify the Sage program below (cf. function f). It is very complicated to write it here. - Petros Hadjicostas, Oct 07 2019

Crossrefs

Column k=8 of A034253 and first differences of A034362.

Programs

  • Sage
    # Fripertinger's method to find the g.f. of column k >= 2 of A034253 (for small k):
    def A034253col(k, length):
        G1 = PSL(k, GF(2))
        G2 = PSL(k-1, GF(2))
        D1 = G1.cycle_index()
        D2 = G2.cycle_index()
        f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
        f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
        f = f1 - f2
        return f.taylor(x, 0, length).list()
    # For instance the Taylor expansion for column k = 8 (current sequence) gives
    print(A034253col(8, 30)) # Petros Hadjicostas, Oct 07 2019

Extensions

More terms from Petros Hadjicostas, Oct 07 2019

A034358 Number of binary [ n,4 ] codes.

Original entry on oeis.org

0, 0, 0, 1, 5, 16, 43, 106, 240, 516, 1060, 2108, 4064, 7641, 14036, 25253, 44560, 77245, 131658, 220883, 365027, 594674, 955649, 1515908, 2374875, 3676632, 5627587, 8520689, 12767557, 18941641, 27834607, 40530902, 58503994, 83741461, 118904892, 167534794, 234309554, 325373538, 448747606
Offset: 1

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Crossrefs

Column k=4 of both A034356 and A076831 (which are the same except for column k=0).
First differences give A034345.

Programs

  • Sage
    # Fripertinger's method to find the g.f. of column k >= 2 of A076831 or A034356 (for small k):
    def A076831col(k, length):
        G1 = PSL(k, GF(2))
        G2 = PSL(k-1, GF(2))
        D1 = G1.cycle_index()
        D2 = G2.cycle_index()
        f1 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D1)
        f2 = sum(i[1]*prod(1/(1-x^j) for j in i[0]) for i in D2)
        f = (f1 - f2)/(1-x)
        return f.taylor(x, 0, length).list()
    # For instance the Taylor expansion for column k = 4 (this sequence) gives
    print(A076831col(4, 30)) # Petros Hadjicostas, Oct 07 2019

Extensions

More terms from Petros Hadjicostas, Oct 07 2019

A034357 Number of binary [ n,3 ] codes.

Original entry on oeis.org

0, 0, 1, 4, 10, 22, 43, 77, 131, 213, 333, 507, 751, 1088, 1546, 2159, 2967, 4023, 5384, 7122, 9322, 12081, 15512, 19752, 24950, 31283, 38953, 48188, 59244, 72419, 88037, 106469, 128129, 153476, 183019, 217331, 257033
Offset: 1

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Comments

Also, a(n) is the number of orbits of C_2^3 subgroups of C_2^n under automorphisms of C_2^n. Also, a(n) is the number of faithful representations of C_2^3 of dimension n up to equivalence by automorphisms of (C_2^3). - Andrew Rupinski, Jan 20 2011

Crossrefs

Column k=3 of both A034356 and A076831 (which are the same except for column k=0).
First differences give A034344.

Formula

G.f.: (-x^15+2*x^14-x^13+x^12+x^9-x^7+x^4+x^3)/((1-x)^3*(1-x^2)*(1-x^3)^2*(1-x^4)*(1-x^7)).

A034359 Number of binary [ n,5 ] codes.

Original entry on oeis.org

0, 0, 0, 0, 1, 6, 23, 77, 240, 705, 1988, 5468, 14724, 39006, 101818, 261924, 663748, 1655781, 4062110, 9793065, 23186825, 53896597, 122975627, 275449464, 605794093, 1308633243, 2777847319, 5797093774, 11900199553, 24042491094, 47833081481, 93765335118, 181200186060, 345389067067, 649704599010
Offset: 1

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Crossrefs

Column k=5 of both A034356 and A076831 (which are the same except for column k=0).
First differences give A034346.

Extensions

More terms from Joerg Arndt, Oct 09 2019

A034360 Number of binary [ n,6 ] codes.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 7, 32, 131, 516, 1988, 7664, 29765, 117169, 467266, 1880517, 7588675, 30491836, 121191234, 473940269, 1816579108, 6806904522, 24897540538, 88831250408, 309108741706, 1049278764758, 3476233500031, 11246972937210, 35561409388625, 109967835029368, 332834886787933, 986732945823099
Offset: 1

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Crossrefs

Column k=6 of both A034356 and A076831 (which are the same except for column k=0).
First differences give A034347.

Extensions

More terms from Joerg Arndt, Oct 09 2019

A034361 Number of binary [ n,7 ] codes.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 8, 43, 213, 1060, 5468, 29765, 173035, 1074526, 7059804, 48235007, 336048291, 2345912476, 16193974418, 109563962854, 722594600193, 4631590699334, 28811338570224, 173868030213652
Offset: 1

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References

  • H. Fripertinger and A. Kerber, in AAECC-11, Lect. Notes Comp. Sci. 948 (1995), 194-204.

Crossrefs

Column k=7 of both A034356 and A076831 (which are the same except for column k=0).
First differences give A034348.
Previous Showing 11-20 of 37 results. Next