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.
%I A289274 #26 Jul 23 2021 02:08:32 %S A289274 46,284,1633,149728,242656,260495,298057,1056752,9587584,17706256, %T A289274 914429696,985501822,1074266048,1484820224,4241800921,12147056128, %U A289274 109548719577,287291764736,360499817799 %N A289274 Numbers k such that the deficiency of k^2 is itself a square > 1. %C A289274 The sequence of square roots of the deficiencies of this sequence is A288144. %C A289274 The disjoint union of the current sequence with the powers of 2 (A000079) is A289275, the sequence of numbers k for which the deficiency of k^2 is a square (including 1). %e A289274 The deficiency of 46^2 is 2*46^2 - sigma(46^2) = 19^2, so 46 is a term of the sequence. %p A289274 issq := n -> evalb(n>1 and issqr(n)): %p A289274 A033879 := n -> 2*n - numtheory[sigma](n): %p A289274 isa := n -> issq(A033879(n^2)): %p A289274 select(isa, [$1..2000]); # _Peter Luschny_, Jul 25 2017 %o A289274 (PARI) isok(n) = issquare(d = 2*n^2 - sigma(n^2)) && (d!=1); \\ _Michel Marcus_, Jul 25 2017 %Y A289274 Cf. A000079, A033879, A288144, A289275. %K A289274 nonn,more %O A289274 1,1 %A A289274 _Jens Voß_, Jun 30 2017 %E A289274 a(10) from _Chai Wah Wu_, Jul 26 2017 %E A289274 a(11)-a(19) from _Giovanni Resta_, Jul 27 2017