cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A244863 Semiprimes whose digit sum is a perfect square.

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%I A244863 #12 Jul 10 2014 03:40:47
%S A244863 4,9,10,22,121,169,178,187,202,259,295,301,358,394,466,493,529,538,
%T A244863 565,583,655,718,745,763,781,799,817,835,862,871,889,898,934,943,961,
%U A244863 979,1003,1111,1159,1177,1186,1195,1267,1285,1294,1339,1357,1366,1393,1438,1465
%N A244863 Semiprimes whose digit sum is a perfect square.
%C A244863 Subsequence of A028839.
%H A244863 K. D. Bajpai, <a href="/A244863/b244863.txt">Table of n, a(n) for n = 1..10000</a>
%e A244863 178 is in the sequence because 178 = 2*89 (semiprime) and 1+7+8 = 16 (square).
%e A244863 187 is in the sequence because 187 = 11*17 (semiprime) and 1+8+7 = 16 (square).
%p A244863 select(n -> numtheory:-bigomega(n)=2 and issqr(convert(convert(n,base,10),`+`)),
%p A244863 [$1..3000]); # _Robert Israel_, Jul 09 2014
%t A244863 Select[Range[3000], PrimeOmega[#] == 2 && IntegerQ[Sqrt[Apply [Plus, IntegerDigits[#]]]] &]
%Y A244863 Cf. A007953, A028839, A048519.
%Y A244863 Cf. A107288 (Primes whose digit sum is square).
%K A244863 nonn,base
%O A244863 1,1
%A A244863 _K. D. Bajpai_, Jul 07 2014