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 A239639 Lengths of runs of the initial digits of semiprimes in decimal representation, cf. A239634 2
 1, 1, 1, 3, 4, 5, 2, 4, 3, 2, 4, 4, 28, 32, 32, 27, 33, 26, 30, 28, 29, 278, 264, 264, 260, 257, 245, 262, 252, 244, 2456, 2380, 2329, 2320, 2254, 2325, 2231, 2244, 2214, 21852, 21400, 20923, 20773, 20548, 20528, 20258, 20156, 20219, 197249, 193162, 190540, 188288, 187308, 185657, 184788, 183856, 183441 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS EXAMPLE .   n | a(n) | runs in A001358 having a common initial digit . ----+------+------------------------------------------------------- .   1 |    1 | [4] .   2 |    1 | [6] .   3 |    1 | [9] .   4 |    3 | [10, 14, 15] .   5 |    4 | [21, 22, 25, 26] .   6 |    5 | [33, 34, 35, 38, 39] .   7 |    2 | [46, 49] .   8 |    4 | [51, 55, 57, 58] .   9 |    3 | [62, 65, 69] .  10 |    2 | [74, 77] .  11 |    4 | [82, 85, 86, 87] .  12 |    4 | [91, 93, 94, 95] .  13 |   28 | [106,111,115,118,119,121,122,123,129,133,134,141, .     |      |  142,143,145,146,155,158,159,161,166,169,177,178, .     |      |  183,185,187,194,201] .  14 |   32 | [201,202,203,205,206,209,213,214,215,217,218,219, .     |      |  221,226,235,237,247,249,253,254,259,262,265,267, .     |      |  274,278,287,289,291,295,298,299] .  15 |   32 | [301,302,303,305,309,314,319,321,323,326,327,329, .     |      |  334,335,339,341,346,355,358,361,362,365,371,377, .     |      |  381,382,386,391,393,394,395,398] .  16 |   27 | [403,407,411,413,415,417,422,427,437,445,446,447, .     |      |  451,453,454,458,466,469,471,473,478,481,482,485, .     |      |  489,493,497]. PROG (Haskell) import Data.List (group) a239639 n = a239639_list !! (n-1) a239639_list = map length \$ group a239634_list CROSSREFS Cf. A001358. Sequence in context: A091828 A305972 A121845 * A099816 A237273 A272025 Adjacent sequences:  A239636 A239637 A239638 * A239640 A239641 A239642 KEYWORD nonn,base AUTHOR Reinhard Zumkeller, Mar 23 2014 STATUS approved

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Last modified August 11 03:22 EDT 2020. Contains 336421 sequences. (Running on oeis4.)