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A161901
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Array read by rows in which row n list the divisors of n, but if n is a square then the square root of n appears repeated.
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4
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1, 1, 1, 2, 1, 3, 1, 2, 2, 4, 1, 5, 1, 2, 3, 6, 1, 7, 1, 2, 4, 8, 1, 3, 3, 9, 1, 2, 5, 10, 1, 11, 1, 2, 3, 4, 6, 12, 1, 13, 1, 2, 7, 14, 1, 3, 5, 15, 1, 2, 4, 4, 8, 16, 1, 17, 1, 2, 3, 6, 9, 18, 1, 19, 1, 2, 4, 5, 10, 20, 1, 3, 7, 21
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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LINKS
| O. E. Pol, Determinacion geometrica de los numeros primos y perfectos
O. E. Pol, Illustration: Divisors and pi(x)
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EXAMPLE
| Array begins:
....... 1,1;
....... 1,2;
....... 1,3;
..... 1,2,2,4;
....... 1,5;
..... 1,2,3,6;
....... 1,7;
..... 1,2,4,8;
..... 1,3,3,9;
..... 1,2,5,10;
....... 1,11;
... 1,2,3,4,6,12;
....... 1,13;
..... 1,2,7,14;
..... 1,3,5,15;
... 1,2,4,4,8,16;
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CROSSREFS
| Cf. A000005, A027750, A038548, A161841, A161842.
Sequence in context: A036989 A035197 A091948 * A102862 A029331 A037269
Adjacent sequences: A161898 A161899 A161900 * A161902 A161903 A161904
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KEYWORD
| easy,nonn,tabf
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Jun 23 2009
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EXTENSIONS
| Keyword tabf added by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 28 2009
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