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A131484
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Numbers n such that A001414(n) divides n+1 and A001414(n+1) divides n.
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1
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44, 41005, 41040, 68263, 91907, 109736, 416325, 603954, 826987, 1122407, 1218999, 1262079, 1533375, 1649375, 1835584, 1935225, 1964199, 2141888, 2562016, 2615799, 2649352, 3021075, 3186000, 3554880, 3863678, 4221536, 4655805
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| There is remote formal resemblance to amicable pairs.
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LINKS
| Klaus Brockhaus, Table of n, a(n) for n=1..126
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EXAMPLE
| 44 = 2*2*11 has sum of prime factors 15, which divides 44 + 1 = 45; 45 = 3*3*5 has sum of prime factors 11, which divides 44. Hence 44 is in the sequence.
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PROG
| (PARI) {m=4700000; s=2; for(n=2, m, f=factor(n+1); t=sum(j=1, matsize(f)[1], f[j, 1]*f[j, 2]); if((n+1)%s==0&&n%t==0, print1(n, ", ")); s=t)} /* Klaus Brockhaus, Jul 30 2007 */
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CROSSREFS
| Cf. A001414 (sum of prime factors of n, with repetition), A063990 (amicable numbers), A130871.
Sequence in context: A172753 A183749 A119096 * A172828 A115734 A119078
Adjacent sequences: A131481 A131482 A131483 * A131485 A131486 A131487
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KEYWORD
| nonn
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AUTHOR
| J. M. Bergot (thekingfishb(AT)yahoo.ca), Jul 28 2007
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EXTENSIONS
| Edited and extended by Stefan Steinerberger (stefan.steinerberger(AT)gmail.com) and Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jul 30 2007
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