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A283944
Interspersion of the signature sequence of Pi (rectangular array by antidiagonals).
2
1, 5, 2, 12, 7, 3, 22, 15, 9, 4, 35, 26, 18, 11, 6, 51, 40, 30, 21, 14, 8, 70, 57, 45, 34, 25, 17, 10, 92, 77, 63, 50, 39, 29, 20, 13, 118, 100, 84, 69, 56, 44, 33, 24, 16, 147, 127, 108, 91, 76, 62, 49, 38, 28, 19, 179, 157, 136, 116, 99, 83, 68, 55, 43, 32
OFFSET
1,2
COMMENTS
Row n is the ordered sequence of numbers k such that A023133(k) = n. As a sequence, it is a permutation of the positive integers. This is a transposable interspersion; i.e., every row intersperses all other rows, and every column intersperses all other columns.
LINKS
Clark Kimberling and John E. Brown, Partial Complements and Transposable Dispersions, J. Integer Seqs., Vol. 7, 2004.
EXAMPLE
Northwest corner:
1 5 12 22 35 51 70 92 118
2 7 15 26 40 57 77 100 127
3 9 18 30 45 63 84 108 136
4 11 21 34 50 69 91 115 145
6 14 25 39 56 76 99 125 155
8 17 29 44 62 83 107 134 165
MATHEMATICA
r = Pi; z = 100;
s[0] = 1; s[n_] := s[n] = s[n - 1] + 1 + Floor[n*r];
u = Table[n + 1 + Sum[Floor[(n - k)/r], {k, 0, n}], {n, 0, z}] (* A022796, col 1 of A283944 *)
v = Table[s[n], {n, 0, z}] (* A022795, row 1 of A283944 *)
w[i_, j_] := u[[i]] + v[[j]] + (i - 1)*(j - 1) - 1;
Grid[Table[w[i, j], {i, 1, 10}, {j, 1, 10}]] (* A283944, array*)
Flatten[Table[w[k, n - k + 1], {n, 1, 20}, {k, 1, n}]] (* A283944, sequence *)
PROG
(PARI)
\\ Produces the triangle when the array is read by antidiagonals
r = Pi;
z = 100;
s(n) = if(n<1, 1, s(n - 1) + 1 + floor(n*r));
p(n) = n + 1 + sum(k=0, n, floor((n - k)/r));
u = v = vector(z + 1);
for(n=1, 101, (v[n] = s(n - 1)));
for(n=1, 101, (u[n] = p(n - 1)));
w(i, j) = u[i] + v[j] + (i - 1) * (j - 1) - 1;
tabl(nn) = {for(n=1, nn, for(k=1, n, print1(w(k, n - k + 1), ", "); ); print(); ); };
tabl(10) \\ Indranil Ghosh, Mar 26 2017
(Python)
# Produces the triangle when the array is read by antidiagonals
import math
from mpmath import *
mp.dps = 100
def s(n): return 1 if n<1 else s(n - 1) + 1 + int(math.floor(n*pi))
def p(n): return n + 1 + sum([int(math.floor((n - k)/pi)) for k in range(0, n+1)])
v=[s(n) for n in range(0, 101)]
u=[p(n) for n in range(0, 101)]
def w(i, j): return u[i - 1] + v[j - 1] + (i - 1) * (j - 1) - 1
for n in range(1, 11):
....print [w(k, n - k + 1) for k in range(1, n + 1)] # Indranil Ghosh, Mar 26 2017
CROSSREFS
KEYWORD
nonn,tabl,easy
AUTHOR
Clark Kimberling, Mar 26 2017
STATUS
approved