OFFSET
1,1
COMMENTS
Numbers k such that A051950(k+1) = 5.
Either k or k+1 is a square. - Amiram Eldar, Apr 17 2024
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
35 is in sequence because tau(36) - tau(35) = 9 - 4 = 5.
MATHEMATICA
Select[ Range[ 50000], DivisorSigma[0, # ] + 5 == DivisorSigma[0, # + 1] &]
PROG
(PARI) lista(kmax) = {my(d); for(k = 2, kmax, d = numdiv(k^2); if(d == numdiv(k^2-1) + 5, print1(k^2-1, ", ")); if(d == numdiv(k^2+1) - 5, print1(k^2, ", "))); } \\ Amiram Eldar, Apr 17 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Nov 03 2013
STATUS
approved