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A264890 Integers k such that k! + 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, 88, 92, 94, 114, 115, 116, 119, 133 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..32.

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!+1)~%4, n[1, i]==3 && n[2, i]%2 && return); n && (vecmin(n[1, ])==1 || (n[1, 1]==2 && n[2, 1]%2)) }

CROSSREFS

Cf. A000404, A038507, A264665, A271186.

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

EXTENSIONS

a(25)-a(32) from Jinyuan Wang, May 22 2021

STATUS

approved

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Last modified September 28 11:24 EDT 2022. Contains 357070 sequences. (Running on oeis4.)