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A067062
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Numbers n such that sigma(n+2)-sigma(n)=prime(n+1)-prime(n).
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1
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3, 5, 17, 40, 41, 203, 1949, 2309, 2711, 2789, 2801, 3299, 3329, 3359, 3917, 4157, 4217, 4259, 4637, 5009, 5021, 5231, 6449, 6497, 7757, 8087, 8219, 8627, 9419, 9929, 10007, 10937, 11777, 12071, 14321, 15647, 15971, 16061, 16901, 18131, 18251
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| If n and n+2, prime(n) and prime(n+1) are twin primes, then n is in the sequence. But some values of n are composite.
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
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MATHEMATICA
| okQ[n_]:=DivisorSigma[1, n+2]-DivisorSigma[1, n]==Prime[n+1]-Prime[n]; Select[Range[20000], okQ] (* From Harvey P. Dale, May 24 2011 *)
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PROG
| (PARI) { default(primelimit, 4294965247); n=0; for (m=1, 10^10, if (sigma(m+2)-sigma(m) == prime(m+1)-prime(m), write("b067062.txt", n++, " ", m); if (n==1000, return)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), May 02 2010]
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CROSSREFS
| Sequence in context: A148517 A148518 A077796 * A148519 A148520 A148521
Adjacent sequences: A067059 A067060 A067061 * A067063 A067064 A067065
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Feb 17 2002
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