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 A047931 Number of new penny-penny contacts when putting pennies on a table following a spiral pattern. 6
 0, 1, 2, 2, 2, 2, 3, 2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 3, 2, 3, 2, 3, 3, 2, 3, 3, 2, 3, 3, 2, 3, 3, 2, 3, 3, 3, 2, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Table of n, a(n) for n=1..91. R. W. Grosse-Kunstleve, Penny Spiral Sequence FORMULA The n-th "chunk" consists of 2 3{n-2} 2 3{n-1} 2 3{n-1} 2 3{n-1} 2 3{n-1} 2 3{n}, where a{b} symbolizes b repetitions of a. EXAMPLE From Omar E. Pol, Nov 16 2016: (Start) The sequence written as a spiral begins: . . 2 - 3 - 3 - 3 - 3 - 2 . / \ . 3 2 - 3 - 3 - 3 - 2 3 . / / \ \ . 3 3 2 - 3 - 3 - 2 3 3 . / / / \ \ \ . 3 3 3 2 - 3 - 2 3 3 3 . / / / / \ \ \ \ . 3 3 3 3 2 - 2 3 3 3 3 . / / / / / \ \ \ \ \ . 2 2 2 2 2 0 - 1 2 2 2 2 . \ \ \ \ \ / / / / . 3 3 3 3 2 - 3 - 2 3 3 3 . \ \ \ \ / / / . 3 3 3 2 - 3 - 3 - 2 3 3 . \ \ \ / / . 3 3 2 - 3 - 3 - 3 - 2 3 . \ \ / . 3 2 - 3 - 3 - 3 - 3 - 2 . \ . 2 - 3 - 3 - 3 - 3 - 3 (End) CROSSREFS Cf. A047932. Sequence in context: A351284 A268317 A234092 * A258571 A033618 A061357 Adjacent sequences: A047928 A047929 A047930 * A047932 A047933 A047934 KEYWORD nonn AUTHOR Ralf W. Grosse-Kunstleve STATUS approved

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Last modified September 26 02:15 EDT 2023. Contains 365649 sequences. (Running on oeis4.)