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 A138254 Balanced prime numbers n such that n*(n-1)-1 is a balanced prime. 0
 10657, 15161, 422911, 691709, 735877, 816239, 1025267, 1030511, 1471891, 1618937, 1683497, 2125411, 2322367, 2448961, 2776157, 2856461, 2880949, 3027319, 3091409, 3114509, 3183337, 3642479, 3797539, 3858091, 3894181, 4752031, 5383387, 5832467, 6052927, 6077821 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..30. EXAMPLE 10657 is balanced prime, 10657*10656-1=113560991 is balanced prime (113560973(prev)+113561009(next))/2=113560991 MATHEMATICA NextPrime[n_Int]:=Module[{k}, k=n+1; While[ !PrimeQ[k], k++ ]; k]; PrevPrime[n_Int]:=Module[{k}, k=n-1; While[ !PrimeQ[k], k-- ]; k]; s=""; For[i=2, i< 10^5, p=Prime[i]; If[(Prime[i-1]+Prime[i+1])/2==p, r=p*(p-1)-1; a=PrevPrime[r]; b=NextPrime[r]; If[PrimeQ[r]&&r==(a+b)/2, (*Print[p, ":", a, ", ", b, "; ", r]*)s=s<>ToString[p]<>", "]]; i++ ]; Print[s] CROSSREFS Cf. A006562. Sequence in context: A013904 A317417 A317418 * A154510 A157326 A207261 Adjacent sequences: A138251 A138252 A138253 * A138255 A138256 A138257 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, May 05 2008 EXTENSIONS a(9)-a(30) from Donovan Johnson, Aug 24 2011 STATUS approved

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Last modified August 6 00:15 EDT 2024. Contains 374957 sequences. (Running on oeis4.)