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A110194 First differences of A110095 (least nonprime sequence whose first differences are nonprime). 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Conjecture: from a(5) on, are there only substrings <1 1 4> and <1 1 1 1 4 4 >?

LINKS

Table of n, a(n) for n=1..49.

EXAMPLE

Beginning with 1, we have to add 8 in order to get the first nonprime number (all other numbers <8 are prime or giving a prime). So 1+8=9 for a(2).

Then add 1=10 for a(3).

Then add (not 1 because 11 is prime; nor 2 and 3 because they are prime) ...add 4=14 for a(4), etc.

CROSSREFS

Cf. A110095 and twin-primes related sequences.

Sequence in context: A011469 A140457 A176457 * A199283 A079359 A010156

Adjacent sequences:  A110191 A110192 A110193 * A110195 A110196 A110197

KEYWORD

easy,nonn

AUTHOR

Alexandre Wajnberg & Eric Angelini, Sep 06 2005

STATUS

approved

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Last modified February 17 12:10 EST 2020. Contains 331996 sequences. (Running on oeis4.)