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 A350337 Sum of the divisors of n that are prime or the product of 2 (not necessarily distinct) primes. 0
 0, 2, 3, 6, 5, 11, 7, 6, 12, 17, 11, 15, 13, 23, 23, 6, 17, 20, 19, 21, 31, 35, 23, 15, 30, 41, 12, 27, 29, 41, 31, 6, 47, 53, 47, 24, 37, 59, 55, 21, 41, 53, 43, 39, 32, 71, 47, 15, 56, 42, 71, 45, 53, 20, 71, 27, 79, 89, 59, 45, 61, 95, 40, 6, 83, 77, 67, 57, 95, 73, 71, 24, 73 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Sum of the divisors of n of the form p, p^2, or p*q, where p and q are prime. LINKS Table of n, a(n) for n=1..73. FORMULA a(n) = Sum_{d|n} d * (u(d) + v(d)), where u is the prime characteristic and v is the semiprime characteristic. a(n) = A008472(n) + A076290(n). - Wesley Ivan Hurt, Jan 02 2024 MATHEMATICA a[n_] := DivisorSum[n, # &, 0 < PrimeOmega[#] <= 2 &]; Array[a, 100] (* Amiram Eldar, Dec 26 2021 *) PROG (PARI) a(n) = sumdiv(n, d, if (isprime(d) || (bigomega(d)==2), d)); \\ Michel Marcus, Dec 26 2021 CROSSREFS Cf. A008472, A010051, A037143, A064911, A076290, A350331. Sequence in context: A340316 A274608 A319680 * A133477 A303695 A345321 Adjacent sequences: A350334 A350335 A350336 * A350338 A350339 A350340 KEYWORD nonn AUTHOR Wesley Ivan Hurt, Dec 25 2021 STATUS approved

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Last modified July 19 02:27 EDT 2024. Contains 374388 sequences. (Running on oeis4.)