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A111440 Squares of the form semiprime(n) + prime(n). 2

%I

%S 9,25,64,81,400,576,1024,1296,2304,2704,4096,7225,7744,10816,14884,

%T 15376,19044,20736,22500,25600,26244,28900,33124,35344,39601,41616,

%U 46656,47961,48400,52900,55225,89401,91204,96100,99856,114921,136900

%N Squares of the form semiprime(n) + prime(n).

%e The first 3 semiprimes are {4,6,9} and the first 3 primes are {2,3,5}. The second term in each are {6,3} whose sum is 9, a square. - _Robert G. Wilson v_

%t sp = Select[ Range[10^5], Plus @@ Last /@ FactorInteger@ # == 2 &]; s = Select[ Range@Length@sp, IntegerQ[ Sqrt[sp[[ # ]] + Prime@# ]] &]; sp[[s]] + Prime[s]; (* _Robert G. Wilson v_ *)

%K nonn

%O 1,1

%A _Giovanni Teofilatto_, Nov 14 2005

%E More terms from _Robert G. Wilson v_, Nov 18 2005

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Last modified September 25 22:13 EDT 2020. Contains 337346 sequences. (Running on oeis4.)