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Search: id:A144650
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| A144650 |
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Triangle read by rows where T(m,n) = 2m*n + m + n + 1. |
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1
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| 5, 8, 13, 11, 18, 25, 14, 23, 32, 41, 17, 28, 39, 50, 61, 20, 33, 46, 59, 72, 85, 23, 38, 53, 68, 83, 98, 113, 26, 43, 60, 77, 94, 111, 128, 145, 29, 48, 67, 86, 105, 124, 143, 162, 181, 32, 53, 74, 95, 116, 137, 158, 179, 200, 221
(list; table; graph; listen)
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OFFSET
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1,1
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COMMENT
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Number n such that 2n-1 is not prime
If 3^n [A003307] belongs to T(m,n), then 2*3^n-1 [A003307] is not prime [From Vincenzo Librandi (vincenzo.librandi(AT)tin.t), Jan 21 2009]
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FORMULA
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Row sum: sum_(n=1..m) T(m,n) = m(2m+3)(m+1)/2 = 5,21,54,110,195,315,... [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 15 2009]
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EXAMPLE
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Triangle begins: 5; 8, 13; 11, 18, 25; 14, 23, 32, 41; 17, 28, 39, 50, 61; 20, 33, 46, 59, 72, 85; 23, 38, 53, 68, 83, 98, 113; 26, 43, 60, 77, 94, 111, 128, 145; 29, 48, 67, 86, 105, 124, 143, 162, 181; 32, 53, 74, 95, 116, 137, 158, 179, 200, 221;
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CROSSREFS
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Cf. A104275
Cf. A003307 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.t), Jan 21 2009]
Sequence in context: A124434 A164128 A078412 this_sequence A046038 A070127 A070128
Adjacent sequences: A144647 A144648 A144649 this_sequence A144651 A144652 A144653
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KEYWORD
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nonn,tabl
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AUTHOR
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Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 13 2009
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