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A106564
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Perfect squares which are not the difference of two primes.
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13
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25, 49, 121, 169, 289, 361, 529, 625, 729, 841, 961, 1225, 1369, 1681, 1849, 2209, 2401, 2601, 2809, 3025, 3481, 3721, 3969, 4225, 4489, 4761, 5041, 5329, 5625, 5929, 6241, 6889, 7225, 7569, 7921, 8281, 8649, 9025, 9409, 10201, 10609, 11449, 11881
(list;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..43.
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FORMULA
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n^2 - A106546 with 0's removed.
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EXAMPLE
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a(2)=49 because it is the second perfect square which is impossible to obtain subtracting a prime from
another one. 64 is not in the sequence because 64=67-3 (difference of two primes).
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MATHEMATICA
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With[{lst=Union[(#[[2]]-#[[1]])&/@Subsets[Prime[Range[2000]], {2}]]}, Select[Range[140]^2, !MemberQ[lst, #]&]] (* From Harvey P. Dale, Jan 04 2011 *)
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CROSSREFS
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Cf. A106544-A106548, A106562-A106563, A106571, A106573-A106575, A106577.
Sequence in context: A110484 A110013 A109861 * A104777 A131706 A110015
Adjacent sequences: A106561 A106562 A106563 * A106565 A106566 A106567
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KEYWORD
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easy,nonn
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AUTHOR
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Alexandre Wajnberg, May 09 2005
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EXTENSIONS
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Extended by Ray Chandler, May 12 2005
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STATUS
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approved
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