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A218731
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a(n) = (28^n-1)/27.
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3
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0, 1, 29, 813, 22765, 637421, 17847789, 499738093, 13992666605, 391794664941, 10970250618349, 307167017313773, 8600676484785645, 240818941573998061, 6742930364071945709, 188802050194014479853, 5286457405432405435885, 148020807352107352204781
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OFFSET
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0,3
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COMMENTS
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Partial sums of powers of 28 (A009972).
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LINKS
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FORMULA
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MATHEMATICA
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PROG
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(Magma) [n le 2 select n-1 else 29*Self(n-1)-28*Self(n-2): n in [1..20]]; // Vincenzo Librandi, Nov 07 2012
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CROSSREFS
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Cf. similar sequences of the form (k^n-1)/(k-1): A000225, A003462, A002450, A003463, A003464, A023000, A023001, A002452, A002275, A016123, A016125, A091030, A135519, A135518, A131865, A091045, A218721, A218722, A064108, A218724-A218734, A132469, A218736-A218753, A133853, A094028, A218723.
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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