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A110095 Least increasing sequence of nonprimes whose first differences are also nonprime. 1
0, 1, 9, 10, 14, 15, 16, 20, 21, 22, 26, 27, 28, 32, 33, 34, 35, 36, 40, 44, 45, 46, 50, 51, 52, 56, 57, 58, 62, 63, 64, 65, 66, 70, 74, 75, 76, 77, 78, 82, 86, 87, 88, 92, 93, 94, 95, 96, 100, 104, 105, 106, 110, 111, 112, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

The sequence of first differences contains only 1's and 4's (with an 8 at the beginning): 1 8 1 4 1 1 4 1 1 4 1 1 4 1 1 1 1 4 4 1 1 4 1 1 4 1 1 4 1 1 1 1 4 4 1 1 1 1 4 4 1 1 4 1 1 1 1 4 4

LINKS

Table of n, a(n) for n=1..65.

EXAMPLE

Begin with a(1)=0. Add to a(1) the least nonprime giving a nonprime number: + 1 = 1 for a(2). Now add to a(2) the least nonprime giving a composite: + 8 = 9 for a(3). Same rule: + 1 = 10 for a(4). Same rule: + 4 = 14 etc...

MATHEMATICA

f[s_List] := Block[{j = s[[ -1]]}, k = j + 1; While[PrimeQ[k] || PrimeQ[k - j], k++ ]; Append[s, k]]; Nest[f, {0}, 64] (* Robert G. Wilson v Sep 23 2006 *)

CROSSREFS

Cf. A109888.

Sequence in context: A189834 A248350 A247512 * A169870 A061445 A261614

Adjacent sequences:  A110092 A110093 A110094 * A110096 A110097 A110098

KEYWORD

easy,nonn

AUTHOR

Alexandre Wajnberg & Eric Angelini, Sep 04 2005

EXTENSIONS

Extended by Ray Chandler, Sep 06 2005

STATUS

approved

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Last modified December 12 15:11 EST 2019. Contains 329960 sequences. (Running on oeis4.)