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Search: id:A152947
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| A152947 |
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a(1)=1; then add 0 to the first number, then 1,2,3,4... and so on. |
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+0
6
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| 1, 1, 2, 4, 7, 11, 16, 22, 29, 37, 46, 56, 67, 79, 92, 106, 121, 137, 154, 172, 191, 211, 232, 254, 277, 301, 326, 352, 379, 407, 436, 466, 497, 529, 562, 596, 631, 667, 704, 742, 781, 821, 862, 904, 947, 991, 1036, 1082, 1129, 1177, 1226, 1276, 1327, 1379
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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basic/fundamental/general sequence(s), similar to Triangular numbers (A000217).
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FORMULA
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a(n) = 1+A000217(n-2) = A000124(n-2), n>1. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 03 2009]
a(n)=n+a(n-1)-2 (with a(1)=1) [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+1-2=1; n=3, a(3)=3+1-2=2; n=4, a(4)=4+2-2=4; n=5, a(5)=5+4-2=7 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 18 2009]
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MATHEMATICA
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s=1; lst={1}; Do[s+=n; AppendTo[lst, s], {n, 0, 5!}]; lst
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PROGRAM
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(Other) SAGE: [1+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.
Sequence in context: A025732 A025739 A000124 this_sequence A098574 A005689 A131075
Adjacent sequences: A152944 A152945 A152946 this_sequence A152948 A152949 A152950
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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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