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A159254
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Numbers whose square ends with 49.
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3
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7, 43, 57, 93, 107, 143, 157, 193, 207, 243, 257, 293, 307, 343, 357, 393, 407, 443, 457, 493, 507, 543, 557, 593, 607, 643, 657, 693, 707, 743, 757, 793, 807, 843, 857, 893, 907, 943, 957, 993, 1007, 1043, 1057, 1093, 1107, 1143, 1157, 1193, 1207, 1243, 1257
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OFFSET
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1,1
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COMMENTS
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First 7 terms = 7th row in A111445.
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LINKS
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FORMULA
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a(1)=7, a(2)=43, a(n) = 50 + a(n-2).
a(n) = (11*(-1)^n + 50*n - 25)/2.
a(n) = a(n-1) + a(n-2) - a(n-3).
G.f.: x*(7*x^2+36*x+7) / ((x-1)^2*(x+1)). (End)
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PROG
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(PARI) select(n->n^2%100==49, vector(10^3, n, n)) \\ Colin Barker, Jul 04 2014
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CROSSREFS
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A111445 Triangle read by rows: row n contains the first n numbers whose squares end in n^2.
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KEYWORD
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base,nonn,easy
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AUTHOR
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STATUS
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approved
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