A270385 Numbers n such that n^2 is a term of A007692 while n is not.

25, 75, 100, 150, 169, 175, 195, 225, 255, 275, 289, 300, 350, 375, 390, 400, 435, 455, 475, 507, 510, 525, 550, 555, 575, 595, 600, 615, 663, 675, 676, 700, 715, 750, 775, 780, 795, 825, 841, 867, 870, 875, 900, 910, 915, 935, 950, 975, 1014, 1015, 1020, 1050, 1075, 1095

Offset

1,1

Comments

Subsequence of A009177.

Links

Table of n, a(n) for n=1..54.

Example

25 is a term because 25 is not a term of A007692 while 25^2 = 625 is a term of A007692.

Mathematica

fQ[n_] := Length@ Select[PowersRepresentations[n, 2, 2], First@ # != 0 &] > 1; Select[Range@1100, And[! fQ@ #, fQ[#^2]] &] (* Michael De Vlieger, May 17 2016 *)

Prog

(PARI) isA007692(n) = {nb = 0; lim = sqrtint(n); for (x=1, lim, if ((n-x^2 >= x^2) && issquare(n-x^2), nb++); ); nb >= 2; }
lista(nn) = for(n=1, nn, if(!isA007692(n) && isA007692(n^2), print1(n, ", ")));

Crossrefs

Cf. A007692, A009177.

Sequence in context: A044163 A044544 A045180 * A053742 A123296 A118610

Adjacent sequences: A270382 A270383 A270384 * A270386 A270387 A270388

Keyword

nonn

Author

Altug Alkan, May 17 2016

Status

approved