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A081931 Diagonal of triangle in A081930. 3

%I

%S 1,22,121,1331,10401,105501,1006001,10077001,100080001,1000990001,

%T 10001010001

%N Diagonal of triangle in A081930.

%p isA002113 := proc(n) local digrev,d ; digrev := convert(n,base,10) ; for d from 1 to nops(digrev)/2 do if op(d,digrev) <> op(-d,digrev) then RETURN(false) ; fi ; od ; RETURN(true) ; end: A081930 := proc(n) local a,k ; a := [] ; k := 10^(n-1) ; while nops(a) < n do if isA002113(k) then a := [op(a),k] ; fi ; k := k+1 ; od ; RETURN(a) ; end: A081931 := proc(n) local nrow ; nrow := A081930(n) ; RETURN(op(-1,nrow)) ; end: for n from 1 to 18 do A081931(n) ; od ; # _R. J. Mathar_, Apr 04 2007

%Y Cf. A081930, A081932.

%K base,more,nonn

%O 1,2

%A _Amarnath Murthy_, Apr 01 2003

%E More terms from _R. J. Mathar_, Apr 04 2007

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Last modified October 26 19:38 EDT 2021. Contains 348268 sequences. (Running on oeis4.)