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A257244
First differences of A256393: a(n) = A256393(n+1) - A256393(n).
5
2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 5, 5, 5, 3, 3, 3, 3, 3, 5, 5, 7, 7, 7, 7, 7, 3, 3, 3, 19, 7, 7, 3, 5, 5, 5, 3, 7, 5, 5, 5, 19, 11, 11, 3, 13, 13, 13, 3, 23, 13, 13, 5, 11, 11, 11, 3, 61, 7, 31, 3, 13, 13, 19, 3, 43, 13, 13, 3, 7, 5, 5, 5, 61, 11, 31, 23, 23, 3, 127, 7, 7, 3, 151, 7, 19, 3, 181, 7, 13, 3, 43, 31, 31
OFFSET
1,1
COMMENTS
Sequence gives the differences between the successive terms of A256393, each difference being equal to their unique shared prime factor.
LINKS
FORMULA
a(n) = A256393(n+1) - A256393(n).
a(n) = gcd(A256393(n+1), A256393(n)).
MATHEMATICA
f[n_] := Block[{pf = First /@ FactorInteger@ n},
If[EvenQ@ n, Max@ pf, Min@ pf]]; s = {2}; lmt = 94; For[k = 2,
k <= lmt, k++, AppendTo[s, s[[k - 1]] + f@ s[[k - 1]]]]; Abs[
Subtract @@@ Partition[s, 2, 1]] (* Michael De Vlieger, Apr 19 2015 *)
PROG
(Scheme, two alternatives)
(define (A257244 n) (- (A256393 (+ n 1)) (A256393 n)))
(define (A257244 n) (gcd (A256393 (+ n 1)) (A256393 n)))
(Haskell)
a257244 n = a257244_list !! (n-1)
a257244_list = zipWith gcd a256393_list $ tail a256393_list
-- Reinhard Zumkeller, May 06 2015
CROSSREFS
Cf. A257245, A257246 (bisections), A257247 (positions where they coincide).
Cf. A256393.
Sequence in context: A072375 A340500 A131981 * A130147 A345377 A096143
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 19 2015
STATUS
approved