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Search: id:A063964
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| A063964 |
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Numbers n such that n and n+1 have the same sum of square-free divisors, or sqf(n)=sqf(n+1), where sqf(n) = A048250(n). |
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+0
1
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| 11, 14, 224, 957, 1334, 1634, 2685, 9347, 13915, 16260, 20145, 20335, 33998, 37236, 42251, 42818, 51624, 55308, 56419, 56975, 71874, 74918, 77748, 79824, 79826, 79833, 84134, 93632, 106600, 111506, 120680, 122073, 138237, 142116, 147454
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,170
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PROGRAM
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(PARI) sqf(n) = sumdiv(n, d, if(issquarefree(d), d, 0)); for(n=1, 10^7, if(sqf(n)==sqf(n+1), print(n)))
(PARI) { n=0; s=0; for (m=1, 10^9, t=sumdiv(m + 1, d, if(issquarefree(d), d, 0)); if(s==t, write("b063964.txt", n++, " ", m); if (n==170, break)); s=t ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 04 2009]
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CROSSREFS
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Cf. A048250.
Sequence in context: A043885 A101840 A061087 this_sequence A139065 A111322 A069822
Adjacent sequences: A063961 A063962 A063963 this_sequence A063965 A063966 A063967
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KEYWORD
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easy,nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Sep 04 2001
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