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A099507
a(n) is such that A099506(a(n)) = n.
5
1, 4, 2, 6, 17, 3, 10, 5, 12, 7, 14, 53, 9, 8, 11, 22, 13, 24, 15, 26, 99, 103, 28, 107, 30, 19, 32, 111, 16, 23, 18, 25, 42, 20, 29, 46, 31, 48, 33, 50, 209, 35, 211, 56, 37, 58, 217, 39, 60, 21, 41, 64, 43, 66, 245, 45, 72, 47, 74, 49, 27, 51, 34, 267, 80, 36, 82, 277, 38, 57
OFFSET
1,2
COMMENTS
a(199) > 10^6 if it exists. - Robert Israel, Jun 17 2015
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000 with 0 for entries greater than 10^6 (if they exist at all)
EXAMPLE
Gives the positions in the sequence A099506 at which the integers n>0 appear. That sequence begins: 1,3,6,2,8,4,... so a(1)=1, a(2)=4, a(3)=2, etc.
PROG
(MATLAB)
N = 10^6;
M = 10*N; % search up to A099506(N) while A099507 < M
% returns 0 for entries not found
B = zeros(1, M);
A = zeros(1, N);
A(1) = 1;
B(1) = 1;
for n = 2:N
t = mod(-A(n-1)-1, n)+1;
bm = t + [0:floor((M-t)/n)]*n;
bz = find(B(bm)==0, 1);
if numel(bz)==0
break
end
m = t + n*(bz-1);
A(n) = m;
B(m) = n;
end;
B(1:1000) % Robert Israel, Jun 17 2015
CROSSREFS
Cf. A099506.
Sequence in context: A053227 A083760 A073597 * A331413 A019104 A019119
KEYWORD
easy,nonn
AUTHOR
Mark Hudson (mrmarkhudson(AT)hotmail.com), Oct 20 2004
STATUS
approved