prog.sf

#!/usr/bin/ruby

# Numbers k such that omega(2^k-1) = omega(2*k-1), where omega(n) = A001221(n).
# https://oeis.org/A355805

# Known terms:
#   1, 2, 3, 5, 7, 11, 13, 19, 23, 31, 53, 59, 61, 67, 101, 103, 109, 131, 149, 167, 179, 193, 197, 227, 241, 269, 353, 373, 389, 443, 457, 487, 599, 607, 881, 941, 971, 1063, 1103, 1117, 1193

include("../../../factordb/auto.sf")

for k in (1..1e4) {
    if (omega(2**k - 1) == omega(2*k - 1)) {
        print(k, ", ")
    }
}

__END__

not FF: 2203965370417376079112624345094737341898230367417432309981854312499294808478943439282878020766213910180655477636091083236938870693224532611198926064989275820116416444371966832753239026754567055860027784245639235357612247714334792858866249442052859722846103523294647549275466059236185776742046818877138927943166299231522734450205122074280821047796929426052641456127