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Search: id:A152948
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| A152948 |
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a(1)=2; then add 0 to the first number, then 1,2,3,4... and so on. |
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+0
4
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| 2, 2, 3, 5, 8, 12, 17, 23, 30, 38, 47, 57, 68, 80, 93, 107, 122, 138, 155, 173, 192, 212, 233, 255, 278, 302, 327, 353, 380, 408, 437, 467, 498, 530, 563, 597, 632, 668, 705, 743, 782, 822, 863, 905, 948, 992, 1037, 1083, 1130, 1178, 1227, 1277, 1328, 1380
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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basic/fundamental/general sequence(s), similar to Triangular numbers (A000217).
Essentially the same as A022856, A089071 and A133263. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 19 2008]
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FORMULA
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a(n)=n+a(n-1)-2 (with a(1)=2) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 18 2009]
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EXAMPLE
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For n=2, a(2)=2+2-2=2; n=3, a(3)=3+2-2=3; n=4, a(4)=4+3-2=5 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 18 2009]
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MATHEMATICA
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s=2; lst={2}; Do[s+=n; AppendTo[lst, s], {n, 0, 5!}]; lst
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PROGRAM
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(Other) SAGE: [2+binomial(n, 2) for n in xrange(0, 54)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 12 2009]
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CROSSREFS
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Cf. A000217, A152947, A000124
Sequence in context: A111123 A087729 A039890 this_sequence A018136 A022863 A039822
Adjacent sequences: A152945 A152946 A152947 this_sequence A152949 A152950 A152951
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KEYWORD
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nonn
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 15 2008
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