cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A261303 a(n+1) = abs(a(n) - gcd(a(n), 3n+2)), a(1) = 1.

Original entry on oeis.org

1, 0, 8, 7, 0, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 71, 70, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9
Offset: 1

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Author

M. F. Hasler, Aug 14 2015

Keywords

Comments

The absolute value is relevant only when a(n) = 0, in which case a(n+1) = gcd(a(n), 3n+2) = 3n+2.
It is conjectured that a(n) = 0 implies that 3n+2 = a(n+1) is prime, for all n > 2, cf. A186255. (This is the sequence {u(n)} mentioned there.)

Crossrefs

Cf. A261301 - A261310, A186253 - A186263, A106108.

Programs

  • PARI
    print1(a=1);for(n=1,199,print1(",",a=abs(a-gcd(a,3*n+2))))
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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