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A112877 Zeros in Cald's sequence: positions n such that A006509(n) = 0. 4
117, 199, 381, 427, 521, 721, 1151, 1997, 3625, 6607, 12269, 23209, 41133, 75441, 141209, 266969, 507701, 968373, 1851971, 3549473, 6817481, 13115259, 25267949, 48750929, 94173137, 182122379 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

A006509(117) = 0 and A006509(k) > 0 for k < 117, so a(1) = 117.

MATHEMATICA

a[1] = 1; a[n_] := a[n] = Block[{b = a[n - 1], p = Prime[n - 1]}, If[ b - p > 0 && Position[t, b - p] == {}, b - p, If[ Position[t, b + p] == {}, b + p, 0]]]; t = {1}; Do[ AppendTo[t, a[n]], {n, 2, 270000}]; Flatten[ Position[t, 0]] (* Robert G. Wilson v *)

CROSSREFS

Cf. A006509, A112878, A117128, A117129.

Sequence in context: A109023 A201021 A187990 * A064180 A050245 A031174

Adjacent sequences:  A112874 A112875 A112876 * A112878 A112879 A112880

KEYWORD

nonn

AUTHOR

Klaus Brockhaus, Oct 24 2005

EXTENSIONS

a(15) and a(16) from Robert G. Wilson v, Oct 29 2005

a(17) and a(18) from Klaus Brockhaus, Jan 01 2006

a(19)-a(26) from Donovan Johnson, Feb 18 2010

STATUS

approved

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Last modified December 18 20:17 EST 2014. Contains 252174 sequences.