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Search: id:A078667
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| A078667 |
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Integers that occur more than once as as the difference [p_n]^2 - [p_(n-1)]^2 of the squares of two consecutive primes. |
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+0
8
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| 72, 120, 168, 312, 408, 552, 600, 768, 792, 912, 1032, 1848, 1848, 2472, 3048, 3192, 3288, 3528, 3720, 4008, 4920, 4920, 4920, 5160, 5208, 5808, 5928, 6072, 6480, 6792, 6840, 6888, 6888, 7080, 7152, 7248, 7512, 7728, 7800, 8520, 8760, 9072, 11400
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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120=31^2-29^2=17^2-13^2
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PROGRAM
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(PARI) pv(v)=vecsort(vecextract(v, concat("1..", vc-1))) op=2; v=vector(5000); vc=1; forprime (p=3, 5000, v[vc]=p^2-op^2; vc++; op=p) v=pv(v) for (i=2, length(v), if (v[i]==v[i-1], print1(v[i]", ")))
(PARI) pv(v)=vecsort(vecextract(v, concat("1..", vc-1))) op=2; v=vector(5000); vc=1; forprime (p=3, 5000, v[vc]= p^2-op^2; vc++; op=p) v=pv(v) for (i=2, length(v), if (v[i]==v[i-1], print1(v[i]", ")))
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CROSSREFS
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Cf. A090783, A090784, A090785, A091878.
Sequence in context: A114128 A143610 A166987 this_sequence A090784 A143741 A157336
Adjacent sequences: A078664 A078665 A078666 this_sequence A078668 A078669 A078670
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KEYWORD
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nonn
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AUTHOR
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Jon Perry (perry(AT)globalnet.co.uk), Dec 15 2002
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