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Search: id:A131874
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| 1, 12, 30, 55, 87, 126, 172, 225, 285, 352, 426, 507, 595, 690, 792, 901, 1017, 1140, 1270, 1407, 1551, 1702, 1860, 2025, 2197, 2376, 2562, 2755, 2955, 3162, 3376, 3597, 3825, 4060, 4302, 4551, 4807, 5070, 5340, 5617, 5901, 6192, 6490, 6795, 7107, 7426
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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Binomial transform of (1, 11, 7, 0, 0, 0,...).
a(n)=7*n+a(n-1)-3 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 09 2009]
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EXAMPLE
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a(2) = 30 = sum of row 2 terms of triangle A131873: (15 + 8 + 7).
a(2) = 30 = (1, 2, 1) dot (1, 11, 7) = (1 + 22 + 7).
For n=2, a(2)=7*2+1-3=12; n=3, a(3)=7*3+12-3=30; n=4, a(4)=7*4+30-3=55 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 09 2009]
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MATHEMATICA
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a[n_]:=Sum[7*i-10, {i, 1, n}]; [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 04 2008]
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CROSSREFS
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Cf. A131873.
Sequence in context: A125582 A031107 A019557 this_sequence A111396 A080385 A120090
Adjacent sequences: A131871 A131872 A131873 this_sequence A131875 A131876 A131877
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KEYWORD
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nonn,new
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), Jul 22 2007
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EXTENSIONS
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More terms and Mathematica program from Orlovsky (4vladimir(AT)gmail.com), Dec 04 2008
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