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 A326147 a(n) = gcd(n-A020639(n), sigma(n)-A020639(n)-n), where A020639 gives the smallest prime factor of n, and sigma is the sum of divisors of n. 4
 1, 1, 2, 1, 4, 4, 6, 1, 1, 2, 10, 2, 12, 4, 6, 1, 16, 1, 18, 2, 2, 4, 22, 2, 1, 2, 2, 26, 28, 4, 30, 1, 6, 2, 2, 1, 36, 4, 2, 2, 40, 4, 42, 2, 6, 4, 46, 2, 1, 1, 6, 2, 52, 4, 2, 2, 2, 2, 58, 2, 60, 4, 2, 1, 2, 4, 66, 2, 6, 4, 70, 1, 72, 2, 2, 2, 2, 4, 78, 26, 1, 2, 82, 2, 2, 4, 6, 2, 88, 2, 14, 2, 2, 4, 10, 2, 96, 1, 6, 1, 100, 4, 102, 2, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Antti Karttunen, Table of n, a(n) for n = 1..20000 FORMULA a(n) = gcd(n-A020639(n), A000203(n)-A020639(n)-n). For n > 1, a(n) = gcd(A046666(n), A326146(n)). PROG (PARI) A020639(n) = if(1==n, n, factor(n)[1, 1]); A326147(n) = gcd(n-A020639(n), sigma(n)-A020639(n)-n); CROSSREFS Cf. A000203, A020639, A046666, A326146, A326148. Cf. also A009194, A325385, A325813, A325975, A326046, A326047, A326048, A326056, A326057, A326060, A326062, A326073, A326129, A326130, A326140, A326144. Sequence in context: A165417 A193631 A190993 * A351168 A196082 A273724 Adjacent sequences: A326144 A326145 A326146 * A326148 A326149 A326150 KEYWORD nonn AUTHOR Antti Karttunen, Jun 10 2019 STATUS approved

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Last modified May 30 13:17 EDT 2023. Contains 363050 sequences. (Running on oeis4.)