{"schema":"vela.problem-packet.v0.1","problem":250,"statement":"Is\\[\\sum \\frac{\\sigma(n)}{2^n}\\]irrational? (Here $\\sigma(n)$ is the sum of divisors function.)","status":"solved","seam":"raw","closureRoutes":[],"obligations":[],"attestations":[],"attempts":[],"velaLean":[],"oeis":[{"id":"A066766","name":"Decimal expansion of Sum_{k>=1} sigma(k)/2^k where sigma(k) is the sum of divisors of k, 1 <= d <= k.","terms":"2,7,4,4,0,3,3,8,8,8,7,5,9,4,8,8,3,6,0,4,8,0,2,1,4,8,9,1,4,9,2,2,7,2,1,6,4,3,1,1,4,2,8,9,8,1,3,1,9,6,3,9,3,1,7,8,4,8,5,2,","url":"https://oeis.org/A066766"}],"generated_note":"derived view; the signed event log is the source of truth (vela check / vela reproduce)"}