OFFSET
1,1
COMMENTS
Conjecture: a(n)>0 for n >= 1.
It would appear that a(3n+1) is greater than either a(3n) or a(3n+2).
Records appear for a(n) for n's: 1, 2, 3, 4, 7, 13, 16, 19, 22, 25, 28, 31, 34, 40, 43, 46, 49, ..., .
LINKS
Robert G. Wilson v, Table of n, a(n) for n = 1..57
MATHEMATICA
f[n_] := f[n] = Block[{p = 3, q = 5, r = 7}, While[p + n*r != (n + 1) q, p = q; q = r; r = NextPrime@ r]; q]; Array[f, 33]
p = 2; q = 3; r = 5; t[_] = 0; While[p < 10^9, If[ Mod[q - p, r - q] == 0 && t[(q - p)/(r - q)] == 0, t[(q - p)/(r - q)] = q; Print[{(q - p)/(r - q), q}]]; p = q; q = r; r = NextPrime@ r]; t@# & /@ Range@45 (* Robert G. Wilson v, Dec 10 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Jan 05 2011
STATUS
approved