This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A264890 Integers n such that n! + 1 is the sum of 2 nonzero squares. 0
 0, 1, 4, 8, 11, 12, 17, 25, 26, 27, 28, 29, 37, 38, 41, 45, 48, 54, 60, 67, 71, 73, 75, 77 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE a(3) = 4 because 4! + 1 = 4^2 + 3^2. MATHEMATICA Flatten@ Position[Map[Length, Map[Map[Length, PowersRepresentations[#, 2, 2] &@(#! + 1) /. 0 -> Nothing] &, Range[0, 48]] /. 1 -> Nothing], n_ /; n > 0] - 1 (* Michael De Vlieger, Nov 28 2015 *) PROG (PARI) is(n) = { for( i=1, #n=factor(n)~%4, n[1, i]==3 && n[2, i]%2 && return); n && ( vecmin(n[1, ])==1 || (n[1, 1]==2 && n[2, 1]%2)) } for(n=0, 1e3, if(is(n!+1), print1(n, ", "))) CROSSREFS Cf. A000404, A038507. Sequence in context: A288150 A311019 A068798 * A272299 A282144 A147515 Adjacent sequences:  A264887 A264888 A264889 * A264891 A264892 A264893 KEYWORD nonn,more AUTHOR Altug Alkan, Nov 27 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 24 06:53 EDT 2019. Contains 323529 sequences. (Running on oeis4.)