1. A plurality of oligonucleotides of different sequence, the oligonucleotides of different sequence covalently linked to separate solid support beads, the oligonucleotides comprising a 3′ random sequence of at least four contiguous nucleotides, a barcode sequence, and one or more nucleotide sequences, the oligonucleotides annealed to a complementary nucleic acid that is complementary to some or all of the nucleotide sequence, wherein the complementary nucleic acid is not complementary to the barcode sequence or the 3′ random sequence, leaving the 3′ random sequence to be single-stranded, wherein the nucleotide sequence is: