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 A256255 Triangle read by rows: T(n,k) = 6*k + 1, n>=0, 0<=k<=(2^n-1). 0
 1, 1, 7, 1, 7, 13, 19, 1, 7, 13, 19, 25, 31, 37, 43, 1, 7, 13, 19, 25, 31, 37, 43, 49, 55, 61, 67, 73, 79, 85, 91, 1, 7, 13, 19, 25, 31, 37, 43, 49, 55, 61, 67, 73, 79, 85, 91, 97, 103, 109, 115, 121, 127, 133, 139, 145, 151, 157, 163, 169, 175, 181, 187, 1, 7, 13, 19, 25, 31, 37, 43, 49, 55, 61, 67, 73, 79, 85, 91, 97, 103 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Row n lists the first 2^n terms of A016921, n >= 0. Row sums give A165665. Right border gives A048488. The sum of all terms of the first k rows gives A060867(k). The product of the terms of the third row is equal to the Hardy-Ramanujan number: 1 * 7 * 13 * 19 = 1729. LINKS EXAMPLE Triangle begins: 1; 1,7; 1,7,13,19; 1,7,13,19,25,31,37,43; 1,7,13,19,25,31,37,43,49,55,61,67,73,79,85,91; ... Illustration of initial terms in the fourth quadrant of the square grid: ------------------------------------------------------------------------ n   a(n)             Compact diagram ------------------------------------------------------------------------ .            _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 0    1      |_|_  |_ _ _  |_ _ _ _ _ _ _  | 1    1      | |_| |_ _  | |_ _ _ _ _ _  | | 2    7      |_ _ _|_  | | |_ _ _ _ _  | | | 3    1      | | | |_| | | |_ _ _ _  | | | | 4    7      | | |_ _ _| | |_ _ _  | | | | | 5   13      | |_ _ _ _ _| |_ _  | | | | | | 6   19      |_ _ _ _ _ _ _|_  | | | | | | | 7    1      | | | | | | | |_| | | | | | | | 8    7      | | | | | | |_ _ _| | | | | | | 9   13      | | | | | |_ _ _ _ _| | | | | | 10  19      | | | | |_ _ _ _ _ _ _| | | | | 11  25      | | | |_ _ _ _ _ _ _ _ _| | | | 12  31      | | |_ _ _ _ _ _ _ _ _ _ _| | | 13  37      | |_ _ _ _ _ _ _ _ _ _ _ _ _| | 14  43      |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _| . a(n) is also the number of cells in the n-th region of the diagram. For other diagrams of the same family see A241717 and A256258. CROSSREFS Cf. A000225, A001235, A016921, A048488, A060867, A165665, A241717, A256258. Sequence in context: A151785 A093564 A081776 * A131115 A151778 A138616 Adjacent sequences:  A256252 A256253 A256254 * A256256 A256257 A256258 KEYWORD nonn,tabf AUTHOR Omar E. Pol, Apr 30 2015 STATUS approved

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Last modified October 16 15:48 EDT 2019. Contains 328101 sequences. (Running on oeis4.)