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A092403
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a(n) = sigma(n) + sigma(n+1).
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7
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4, 7, 11, 13, 18, 20, 23, 28, 31, 30, 40, 42, 38, 48, 55, 49, 57, 59, 62, 74, 68, 60, 84, 91, 73, 82, 96, 86, 102, 104, 95, 111, 102, 102, 139, 129, 98, 116, 146, 132, 138, 140, 128, 162, 150, 120, 172, 181, 150, 165, 170, 152, 174, 192, 192, 200, 170, 150, 228, 230
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OFFSET
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1,1
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COMMENTS
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a(n) is the area of the terrace in the level 1 of the polycube called "tower" described in A221529 where the longest side of its base is equal to n + 1, thus a(n) has a symmetric representation. - Omar E. Pol, Jul 22 2021
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LINKS
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FORMULA
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MATHEMATICA
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Total/@Partition[DivisorSigma[1, Range[70]], 2, 1] (* Harvey P. Dale, Feb 19 2018 *)
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PROG
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(PARI) for(i=1, 60, print1(", "sigma(i)+sigma(i+1)))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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