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A136110
Limiting sequence when we start with the positive integers (A000027) and delete in step n >= 1 the term at position n + tau(a(n)), where tau(k) is the number of divisors of k.
4
1, 3, 4, 6, 7, 9, 12, 13, 15, 17, 18, 22, 23, 24, 28, 29, 30, 32, 33, 36, 37, 38, 43, 44, 47, 49, 51, 52, 55, 56, 58, 59, 62, 65, 66, 68, 70, 72, 73, 74, 78, 79, 80, 84, 85, 86, 88, 90, 92, 94, 96, 97, 98, 104, 105, 106, 108, 109, 111, 116, 118, 119, 121, 122, 126, 129, 130
OFFSET
1,2
LINKS
D. X. Charles, Sieve Methods, July 2000, University of Wisconsin.
M. C. Wunderlich, A general class of sieve generated sequences, Acta Arithmetica XVI,1969, pp.41-56.
EXAMPLE
First few steps are:
1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,...
n = 1; delete term at position 1+tau(1) = 1+1 =2: 2;
1,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,...
n = 2; delete term at position 2+tau(3) = 1+2 = 3: 5;
1,3,4,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,...
n = 3; delete term at position 3+tau(4) = 3+3 = 6: 8;
1,3,4,6,7,9,10,11,12,13,14,15,16,17,18,19,20,...
n = 4; delete term at position 4+tau(6) = 4+4 = 8: 11;
1,3,4,6,7,9,10,12,13,14,15,16,17,18,19,20,...
n = 5; delete term at position 5+tau(7) = 5+2 = 7: 10;
1,3,4,6,7,9,12,13,14,15,16,17,18,19,20,...
n = 6; delete term at position 6+tau(9) = 6+3 = 9: 14;
1,3,4,6,7,9,12,13,15,16,17,18,19,20,...
CROSSREFS
Cf. A000005 (number of divisors), A000027, A137292, A138899, A138900.
Sequence in context: A201471 A338387 A360799 * A032725 A089038 A336175
KEYWORD
easy,nonn
AUTHOR
Ctibor O. Zizka, Mar 16 2008
EXTENSIONS
Edited and extended by Klaus Brockhaus, Apr 03 2008
Moved references to the Links section R. J. Mathar, Oct 23 2009
STATUS
approved