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.

A328631 Square array where the row n lists all nonnegative numbers k for which A328578(k) = n, read by falling antidiagonals.

Original entry on oeis.org

1, 3, 0, 5, 12, 2, 7, 24, 6, 4, 9, 30, 18, 8, 10, 11, 42, 34, 16, 14, 20, 13, 54, 36, 32, 38, 22, 28, 15, 60, 48, 64, 58, 26, 50, 82, 17, 72, 66, 152, 62, 40, 52, 88, 116, 19, 84, 78, 184, 112, 44, 56, 106, 118, 148, 21, 90, 96, 210, 166, 46, 74, 110, 140, 178, 208, 23, 102, 108, 242, 176, 68, 76, 128, 142, 196, 412, 418
Offset: 1

Views

Author

Antti Karttunen, Oct 27 2019

Keywords

Comments

Array is read by descending antidiagonals with (n,k) = (1,1), (1,2), (2,1), (1,3), (2,2), (3,1), ... where A(n,k) is the k-th solution x to A328578(x) = n.

Examples

			The top left 12 X 12 corner of the array:
   n +------------------------------------------------------
   1 |   1,   3,   5,   7,   9,  11,  13,  15,  17,  19, ...
   2 |   0,  12,  24,  30,  42,  54,  60,  72,  84,  90, ...
   3 |   2,   6,  18,  34,  36,  48,  66,  78,  96, 108, ...
   4 |   4,   8,  16,  32,  64, 152, 184, 210, 242, 274, ...
   5 |  10,  14,  38,  58,  62, 112, 166, 176, 214, 218, ...
   6 |  20,  22,  26,  40,  44,  46,  68,  70,  86,  92, ...
   7 |  28,  50,  52,  56,  74,  76,  80,  94,  98, 100, ...
   8 |  82,  88, 106, 110, 128, 130, 134, 158, 182, 262, ...
   9 | 116, 118, 140, 142, 146, 160, 164, 170, 188, 190, ...
  10 | 148, 178, 196, 200, 202, 206, 328, 352, 374, 376, ...
  11 | 208, 412, 416, 562, 568, 586, 590, 592, 596, 614, ...
  12 | 418, 598, 626, 628, 778, 800, 802, 826, 830, 832, ...
		

Crossrefs

Programs

  • PARI
    up_to = 78;
    A257993(n) = { for(i=1,oo,if(n%prime(i),return(i))); }
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A328578(n) = A257993(A276086(A276086(n)));
    memoA328631sq = Map();
    A328631sq(n, k) = { my(v=0); if(!mapisdefined(memoA328631sq,[n,k-1],&v),if(1==k, v=-1, v = A328631sq(n, k-1))); for(i=1+v,oo,if(A328578(i)==n,mapput(memoA328631sq,[n,k],i); return(i))); };
    A328631list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A328631sq(col,(a-(col-1))))); (v); };
    v328631 = A328631list(up_to);
    A328631(n) = v328631[n];