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A160522
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The n-th odd composite number minus the n-th even composite number.
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3
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5, 9, 13, 15, 15, 19, 19, 21, 25, 27, 27, 29, 29, 33, 33, 35, 39, 39, 41, 43, 43, 45, 45, 45, 47, 51, 55, 57, 57, 57, 57, 57, 57, 59, 61, 61, 65, 65, 65, 65, 69, 69, 71, 71, 73, 75, 75, 77, 77, 81, 81, 81, 81, 85, 89, 89, 89, 89, 89, 91, 91, 91, 91, 91, 93, 97, 99, 99, 103, 103
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| K. Stern, Table of n, a(n) for n=1..1000
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FORMULA
| a(n) = A071904(n) - A005843(n+1).
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PROG
| (Other) %% Matlab code to generate n-th odd composite minus n-th even composite function [a] = A160522(k) j = 1; n = 1; even = 4; while j < k n = n + 1; if isprime(n) == 1 else if mod(n, 2) == 0 else a(j, 1) = n - even; even = even + 2; j = j + 1; end end end
(PARI) {m=70; v=vector(m); k=4; n=0; while(n<m, if(k%2>0&&!isprime(k), n++; v[n]=k-2*(n+1)); k++); v} [From Klaus Brockhaus, May 22 2009]
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CROSSREFS
| Cf. A002808, A005843, A071904.
Cf. A047846 [From Kyle Stern (kstern1(AT)umbc.edu), Jun 01 2009]
Sequence in context: A130333 A080579 A165971 * A194371 A062976 A080580
Adjacent sequences: A160519 A160520 A160521 * A160523 A160524 A160525
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KEYWORD
| easy,nonn
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AUTHOR
| Kyle Stern (kstern1(AT)umbc.edu), May 16 2009
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EXTENSIONS
| Extended and formula edited by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), May 22 2009
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