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A089697 Smallest n-digit number k such that k+1 as well as 1 + the product of digits of k are squares greater than 1. 1

%I #9 Aug 20 2017 10:53:55

%S 3,24,168,1443,12543,118335,1223235,11323224,111218115,1112622735,

%T 11127718143,111234256323,1111183732128,11112128912195,

%U 111121198291215,1111117422231183,11111117364211224,111111275555616399,1111251521961995715,11111411997592513155,111111316155511267599,1111115159292576131135,11111135171219693125155,111111619512137115332355

%N Smallest n-digit number k such that k+1 as well as 1 + the product of digits of k are squares greater than 1.

%p readlib(issqr): Digits:=100: for d from 1 to 20 do for n from ceil(sqrt((10^d-1)/9+1)) to floor(sqrt(10^d)) do m:=mul(j,j=convert(n^2-1,base,10)): if m<>0 and issqr(m+1) then printf("%d, ",n^2-1): break fi od od: # C. Ronaldo

%Y Cf. A081990, A089698.

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Nov 10 2003

%E More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 25 2004

%E Definition clarified and a(21)-a(24) added by _Chai Wah Wu_, Aug 19 2017

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Last modified March 29 02:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)