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 1-7 of 7 results.

A026100 a(n) = number of the column of A026098 that contains n.

Original entry on oeis.org

1, 2, 1, 3, 1, 2, 1, 4, 3, 2, 1, 4, 1, 2, 3, 5, 1, 5, 1, 4, 3, 2, 1, 6, 5, 2, 6, 4, 1, 7, 1, 8, 3, 2, 5, 7, 1, 2, 3, 6, 1, 6, 1, 4, 7, 9, 1, 8, 7, 8, 3, 4, 1, 9, 5, 10, 3, 2, 1, 9, 1, 11, 8, 12, 5, 6, 1, 4, 2, 9, 1, 10, 1, 2, 10, 4, 7, 6, 1, 11, 11, 13, 1, 10, 5, 14, 3, 8, 1, 12, 7, 3, 2, 15, 5, 13, 1, 11, 9, 12
Offset: 1

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Author

Keywords

Crossrefs

Cf. A026098.

Programs

  • PARI
    getrow(n, all) = {if (n==1, return ([1])); if (n==2, return ([3, 2])); my(row = vector(n)); row[1] = prime(n); for (k=2, n, my(ok = 0, m = 1, val); until(ok, val = m*prime(n+1-k); if (!setsearch(all, val) && !setsearch(Set(row), val), ok = 1); m++; ); row[k] = val; ); return (row); };
    A026100list(up_to_row) = { my(all = [], m = Map(), lista = List([]), u); for(n=1, up_to_row, my(row = getrow(n, all)); for(k=1, n, mapput(m,row[k],k)); all = Set(concat(all, row))); for(n=1,oo,if(mapisdefined(m,n,&u), listput(lista,u), if(isprime(n)&&(n>2),listput(lista,1), return(Vec(lista))))); };
    v026100 = A026100list(1200);
    A026100(n) = v026100[n]; \\ Antti Karttunen, Jan 18 2020, after program in A026098 provided by Michel Marcus.

Extensions

a(27) onward corrected by Sean A. Irvine, Sep 15 2019

A070264 Inverse permutation to that in A026098.

Original entry on oeis.org

1, 3, 2, 6, 4, 5, 7, 10, 9, 8, 11, 14, 16, 12, 13, 15, 22, 20, 29, 19, 18, 17, 37, 21, 26, 23, 27, 25, 46, 28, 56, 36, 24, 30, 33, 35, 67, 38, 31, 34, 79, 42, 92, 32, 43, 45, 106, 44, 52, 53, 39, 40, 121, 54, 41, 55, 48, 57, 137, 64, 154, 66, 63, 78, 50, 51, 172, 49, 47, 75
Offset: 1

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Author

Antti Karttunen, May 07 2002

Keywords

Extensions

More terms from David Wasserman, Aug 12 2002

A026099 Row of A026098 that contains n.

Original entry on oeis.org

1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 6, 5, 5, 5, 7, 6, 8, 6, 6, 6, 9, 6, 7, 7, 7, 7, 10, 7, 11, 8, 7, 8, 8, 8, 12, 9, 8, 8, 13, 9, 14, 8, 9, 9, 15, 9, 10, 10, 9, 9, 16, 10, 9, 10, 10, 11, 17, 11, 18, 11, 11, 12, 10, 10, 19, 10, 10, 12, 20, 11, 21, 13, 12, 11, 11, 11, 22, 13, 12, 13, 23, 13, 11, 14, 12, 12, 24, 13, 12, 11, 12, 15, 12, 14, 25, 14, 13, 14
Offset: 1

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Author

Keywords

Extensions

a(24) onward corrected by Sean A. Irvine, Sep 15 2019

A026101 T(n,1) + T(n,2) + ... T(n,n), where T is the array in A026098.

Original entry on oeis.org

1, 5, 15, 34, 68, 118, 186, 279, 400, 563, 754, 998, 1265, 1614, 2015, 2468, 3023, 3610, 4277, 4980, 5795, 6734, 7754, 8847, 10170, 11502, 13002, 14661, 16373, 18150, 20212, 22351, 24465, 26949, 29608, 32312, 35295, 38459, 41644, 45192, 48910, 52858, 56965, 61291, 65677
Offset: 1

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Author

Keywords

Extensions

a(6) onward corrected by Sean A. Irvine, Sep 15 2019

A026102 a(n) = T(2n-1,n), where T is the array in A026098.

Original entry on oeis.org

1, 6, 15, 28, 55, 78, 119, 152, 230, 290, 372, 444, 574, 645, 752, 901, 1062, 1159, 1273, 1491, 1606, 1817, 1992, 2314, 2522, 2828, 2987, 3210, 3270, 3616, 4191, 4323, 4658, 5004, 5364, 5738, 6123, 6357, 6847, 7266, 7697, 7964, 8595, 8685, 9259, 9552, 10339, 10927, 11577, 11908
Offset: 1

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Author

Keywords

Crossrefs

Cf. A033286. [R. J. Mathar, Oct 22 2008]

Programs

  • Mathematica
    T[1, 1] = 1; T[2, 1] = 3; T[2, 2] = 2; T[n_, 1] := Prime[n];
    T[n_, k_] := T[n, k] = Module[{m, mp, jtt}, For[m = 1, True, m++, mp = m Prime[n+1-k]; jtt = Join[Table[T[i, j], {i, 1, n-1}, {j, 1, i}] // Flatten, Table[T[n, j], {j, 1, k-1}]]; If[FreeQ[jtt, mp], Return[mp]]]];
    a[n_] := T[2n-1, n]; (* Jean-François Alcover, Sep 05 2019 *)
  • PARI
    lista(nn) = {my(all = []); for (n=1, nn, my(row = getrow(n, all)); if (n % 2, print1(row[(n+1)/2], ", ")); all = Set(concat(all, row)););} \\ uses getrow from A026098; Michel Marcus, Sep 04 2019

Formula

a(n) = A026098(A001844(n)). - Sean A. Irvine, Sep 16 2019

Extensions

Corrected and extended by Michel Marcus, Sep 04 2019

A026103 a(n) = T(n,1) + T(n-1,2) + ...+ T(n-k+1,k), where k = floor((n+1)/2) and T is the array defined in A026098.

Original entry on oeis.org

1, 3, 7, 13, 25, 36, 62, 78, 126, 152, 244, 266, 419, 423, 637, 679, 932, 1007, 1307, 1419, 1697, 1918, 2229, 2514, 2899, 3300, 3672, 4223, 4663, 5298, 5682, 6495, 6988, 7619, 8324, 9289, 9861, 11033, 11697, 12812, 13727, 14956, 16008, 17298, 18473, 19701, 21186, 22502
Offset: 1

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Author

Keywords

Comments

a(n) is the sum of the terms of the n-th antidiagonal of triangle A026098. - Sean A. Irvine, Sep 16 2019

Extensions

a(11) onward corrected and more terms from Sean A. Irvine, Sep 16 2019

A026104 a(n) = greatest number in row n of A026098 that is not a positive power of 2.

Original entry on oeis.org

1, 3, 6, 10, 15, 24, 33, 44, 55, 69, 92, 115, 138, 161, 186, 217, 248, 287, 328, 369, 410, 451, 492, 533, 590, 649, 708, 767, 826, 885, 944, 1003, 1068, 1157, 1246, 1335, 1424, 1515, 1616, 1717, 1818, 1919, 2020, 2121, 2222, 2323, 2424, 2540, 2667, 2794, 2921
Offset: 1

Views

Author

Keywords

Extensions

Corrected and extended by David Wasserman, Aug 12 2002
Showing 1-7 of 7 results.