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Search: id:A086284
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| A086284 |
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Number of prime squares with maximum integer n (see comment for definition). |
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+0
1
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| 1, 3, 5, 11, 14, 21, 29, 37, 56, 88, 110, 145, 171, 197, 241, 302, 347, 392, 438, 484, 555, 650, 717, 806, 916, 1026, 1180, 1334, 1451, 1600, 1765, 1930, 2101, 2315, 2539, 2816, 3108, 3400, 3702, 4063
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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A prime square is constructed by drawing a square, and placing a positive integer at each corner. All adjacent corners must sum to a prime. The maximum integer is the largest integer that may be used.
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EXAMPLE
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a(4)=11 since we have the 2 X 2 squares:
11 21 21 32 32 41 43 43 43 43 41
11 11 12 21 23 14 14 34 12 32 12
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PROGRAM
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(PARI) { ps(n)=local(s); s=2; forstep (i1=1, n, 2, forstep (i2=2, n, 2, forstep (i3=i1, n, 2, forstep (i4=i2, n, 2, if (isprime(i1+i2) && isprime(i2+i3) && isprime(i3+i4) && isprime(i4+i1), s++))))); if (n==1, s=1); if (n==2, s=3); s } for (i=1, 40, print1(ps(i)", "))
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CROSSREFS
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Adjacent sequences: A086281 A086282 A086283 this_sequence A086285 A086286 A086287
Sequence in context: A032457 A122564 A058595 this_sequence A136500 A024897 A048702
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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), Aug 28 2003
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