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 1-3 of 3 results.

A286560 Compound filter (summands of A004001 & summands of A005185): a(n) = P(A286541(n), A286559(n)), where P(n,k) is sequence A000027 used as a pairing function, with a(1) = a(2) = 0.

Original entry on oeis.org

0, 0, 1, 2, 5, 41, 71, 71, 198, 313, 484, 922, 1153, 1201, 2105, 1565, 2588, 4046, 5001, 7443, 7443, 8851, 10671, 19589, 16570, 16935, 22254, 25313, 25313, 25313, 42891, 28793, 32768, 52795, 65504, 59178, 73355, 89033, 88632, 107660, 129045, 129045, 153471, 167646, 167646, 182446, 182446, 336130, 197244, 233297, 330472, 307358, 270167, 355325, 378466, 332156
Offset: 1

Views

Author

Antti Karttunen, May 18 2017

Keywords

Crossrefs

Programs

Formula

a(1) = a(2) = 0, for n > 2, a(n) = (1/2)*(2 + ((A286541(n)+A286559(n))^2) - A286541(n) - 3*A286559(n)).

A286541 Compound filter (the left & right summand of Hofstadter-Conway $10000 sequence): a(n) = P(A004001(A004001(n-1)), A004001(n-A004001(n-1))), where P(n,k) is sequence A000027 used as a pairing function, with a(1) = a(2) = 0.

Original entry on oeis.org

0, 0, 1, 1, 2, 5, 5, 5, 8, 13, 19, 19, 25, 25, 25, 25, 32, 41, 51, 62, 62, 73, 86, 86, 99, 99, 99, 113, 113, 113, 113, 113, 128, 145, 163, 182, 202, 202, 222, 244, 267, 267, 290, 315, 315, 340, 340, 340, 366, 394, 394, 422, 422, 422, 451, 451, 451, 451, 481, 481, 481, 481, 481, 481, 512, 545, 579, 614, 650, 687, 687, 724, 763, 803, 844, 844, 885, 928, 972, 972
Offset: 1

Views

Author

Antti Karttunen, May 18 2017

Keywords

Crossrefs

Programs

Formula

a(1) = a(2) = 0, for n > 2, a(n) = (1/2)*(2 + ((A004001(A004001(n-1))+A004001(n-A004001(n-1)))^2) - A004001(A004001(n-1)) - 3*A004001(n-A004001(n-1))).

A302779 Restricted growth sequence transform of ordered pair [Q(n-Q(n-1)), Q(n-Q(n-2))], the left & right summand of Hofstadter Q-sequence A005185.

Original entry on oeis.org

1, 1, 2, 3, 3, 4, 5, 5, 6, 6, 6, 7, 8, 7, 9, 10, 9, 11, 11, 12, 12, 12, 12, 13, 14, 15, 13, 13, 13, 13, 16, 17, 18, 16, 19, 20, 21, 22, 19, 22, 23, 23, 24, 24, 24, 24, 24, 25, 26, 27, 28, 29, 30, 31, 28, 32, 25, 28, 25, 25, 25, 25, 33, 34, 35, 36, 37, 38, 39, 33, 40, 36, 41, 42, 43, 39, 44, 43, 45, 46, 47, 48, 48, 49, 50, 51, 52, 52, 49, 53, 53, 53, 53, 53, 53
Offset: 1

Views

Author

Antti Karttunen, Apr 27 2018

Keywords

Comments

Restricted growth sequence transform of A286559.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    first_n_of_A005185(n) = { my(v=vector(n)); v[1]=v[2]=1; for(k=3, n, v[k]=v[k-v[k-1]]+v[k-v[k-2]]); (v); };
    v005185 = first_n_of_A005185(up_to);
    A005185(n) = v005185[n];
    Aux302779(n) = if(n<3,0,[A005185(n-A005185(n-1)), A005185(n-A005185(n-2))]);
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    write_to_bfile(1,rgs_transform(vector(up_to,n,Aux302779(n))),"b302779.txt");
Showing 1-3 of 3 results.