if (i == nrequest) b <- N
URL <- paste("http://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=nucleotide&id=",
paste(access.nb[a:b], collapse = ","),
if (i == nrequest) b <- N
URL <- paste("http://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=nucleotide&id=",
paste(access.nb[a:b], collapse = ","),