

A110278


Values of n such that the perfect deficiency (A109883) of n and n+1 are both squares.


1




OFFSET

1,2


COMMENTS

Conjecture: sequence is infinite.


LINKS



EXAMPLE

A109883(37)=36 & A109883(38)=16, both of which are squares, so 37 is a term.


MATHEMATICA

subtract = If[ #1 < #2, Throw[ #1], #1  #2]&; f[n_] := Catch @ Fold[subtract, n, Divisors @ n]; a = False; Do[b = IntegerQ[ Sqrt[ f[ n]]]; If[{a, b} == {True, True}, Print[n  1]]; a = b, {n, 10^7}] (* Robert G. Wilson v, Jul 21 2005 *)


PROG

(PARI) a109883(n) = {my(r = n); fordiv(n, d, if (r < d, return (r)); r = d; ); 0; }
isok(n) = issquare(a109883(n)) && issquare(a109883(n+1)); \\ Michel Marcus, Dec 28 2018


CROSSREFS



KEYWORD

more,nonn


AUTHOR



EXTENSIONS



STATUS

approved



