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A180600
a(n+1) = a(n) if A180458(n+1) = A180458(n), otherwise a(n+1) = a(n)+1.
1
1, 2, 3, 4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9, 10, 10, 10, 11, 11, 12, 12, 13, 13, 13, 13, 14, 15, 16, 16, 16, 17, 18, 18, 19, 19, 20, 20, 21, 22, 22, 22, 22, 23, 24, 24, 24, 25, 25, 25, 26, 27, 28, 28, 28, 29, 29, 30, 31, 32, 32, 33, 33, 34, 35, 36, 36, 37, 37, 38, 39, 39, 40, 40, 41
OFFSET
1,2
COMMENTS
This arithmetic sequence grows with slope 1 where A180458 increases, and has terraces (zero slope) where A180458 has terraces.
LINKS
FORMULA
a(n+1) = a(n) + min(1, A180458(n+1)-A180458(n)). - R. J. Mathar, Oct 24 2010
MAPLE
isA002113 := proc(n) n = digrev(n) ; end proc:
A180458 := proc(n) local p ; p := ithprime(n) ; while not isA002113(p) do p := p-1 ; end do; p ; end proc:
A180600 := proc(n) option remember; if n = 1 then 1; else if A180458(n) = A180458(n-1) then procname(n-1) ; else procname(n-1)+1 ; end if; end if; end proc:
seq(A180600(n), n=1..90) ; # R. J. Mathar, Oct 24 2010
MATHEMATICA
lpn[n_]:=Module[{k=0}, While[!PalindromeQ[n-k], k++]; n-k]; nxt[{n_, l_, a_}] := Module[{x=lpn[Prime[n+1]]}, {n+1, x, If[x==l, a, a+1]}]; NestList[ nxt, {1, 1, 1}, 80][[All, 3]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 18 2020 *)
CROSSREFS
Sequence in context: A087829 A078474 A087177 * A006159 A376194 A081610
KEYWORD
easy,nonn,base
AUTHOR
Giovanni Teofilatto, Sep 11 2010
EXTENSIONS
Sequence corrected starting near a(54), definition corrected, comment and formula added by R. J. Mathar, Oct 24 2010
STATUS
approved