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 A261348 a(1)=0; a(2)=0; for n>2: a(n) = A237591(n,2) = A237593(n,2). 1
 0, 0, 1, 1, 2, 1, 2, 2, 2, 2, 3, 2, 3, 3, 3, 3, 4, 3, 4, 4, 4, 4, 5, 4, 5, 5, 5, 5, 6, 5, 6, 6, 6, 6, 7, 6, 7, 7, 7, 7, 8, 7, 8, 8, 8, 8, 9, 8, 9, 9, 9, 9, 10, 9, 10, 10, 10, 10, 11, 10, 11, 11, 11, 11, 12, 11, 12, 12, 12, 12, 13, 12, 13, 13, 13, 13, 14, 13, 14, 14, 14, 14, 15, 14, 15, 15, 15, 15, 16, 15, 16, 16, 16, 16, 17, 16 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 COMMENTS n is an odd prime if and only if a(n) = 1 + a(n-1) and A237591(n,k) = A237591(n-1,k) for the values of k distinct of 2. For k > 1 there are five numbers k in the sequence. For more information see A237593. LINKS EXAMPLE Apart from the initial two zeros the sequence can be written as an array T(j,k) with 6 columns, where row j is [j, j, j+1, j, j+1, j+1], as shown below: 1,   1,  2,  1,  2,  2; 2,   2,  3,  2,  3,  3; 3,   3,  4,  3,  4,  4; 4,   4,  5,  4,  5,  5; 5,   5,  6,  5,  6,  6; 6,   6,  7,  6,  7,  7; 7,   7,  8,  7,  8,  8; 8,   8,  9,  8,  9,  9; 9,   9, 10,  9, 10, 10; 10, 10, 11, 10, 11, 11; 11, 11, 12, 11, 12, 12; 12, 12, 13, 12, 13, 13; 13, 13, 14, 13, 14, 14; 14, 14, 15, 14, 15, 15; 15, 15, 16, 15, 16, 16; ... Illustration of initial terms: Row                                                     _ 1                                                     _| |0 2                                                   _|  _|0 3                                                 _|   |1| 4                                               _|    _|1| 5                                             _|     |2 _| 6                                           _|      _|1| | 7                                         _|       |2  | | 8                                       _|        _|2 _| | 9                                     _|         |2  |  _| 10                                  _|          _|2  | | | 11                                _|           |3   _| | | 12                              _|            _|2  |   | | 13                            _|             |3    |  _| | 14                          _|              _|3   _| |  _| 15                        _|               |3    |   | | | 16                      _|                _|3    |   | | | 17                    _|                 |4     _|  _| | | 18                  _|                  _|3    |   |   | | 19                _|                   |4      |   |  _| | 20              _|                    _|4     _|   | |  _| 21            _|                     |4      |    _| | | | 22          _|                      _|4      |   |   | | | 23        _|                       |5       _|   |   | | | 24      _|                        _|4      |     |  _| | | 25    _|                         |5        |    _| |   | | 26   |                           |5        |   |   |   | | ... The figure represents the triangle A237591 in which the numbers of horizontal cells in the second geometric region gives this sequence, for n > 2. Note that this is also the second geometric region in the front view of the step pyramid described in A245092. For more information see also A237593. CROSSREFS Cf. A000040, A236104, A235791, A237048, A237591, A237593, A261350, A261699. Sequence in context: A008615 A103221 A026806 * A320536 A298783 A053280 Adjacent sequences:  A261345 A261346 A261347 * A261349 A261350 A261351 KEYWORD nonn,tabf,easy AUTHOR Omar E. Pol, Aug 24 2015 STATUS approved

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Last modified December 6 18:03 EST 2019. Contains 329809 sequences. (Running on oeis4.)