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 A097272 Least integer with same "mod 2 prime signature" as n. 5
 1, 2, 3, 4, 3, 6, 3, 8, 9, 6, 3, 12, 3, 6, 15, 16, 3, 18, 3, 12, 15, 6, 3, 24, 9, 6, 27, 12, 3, 30, 3, 32, 15, 6, 15, 36, 3, 6, 15, 24, 3, 30, 3, 12, 45, 6, 3, 48, 9, 18, 15, 12, 3, 54, 15, 24, 15, 6, 3, 60, 3, 6, 45, 64, 15, 30, 3, 12, 15, 30, 3, 72, 3, 6, 45, 12, 15, 30, 3, 48, 81, 6, 3, 60 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For n = 2^a_0 * p_1^a_1 * ... * p_n^a_n where p_i is odd prime and a_1 >= a_2 >= ... >= a_n, define "mod 2 prime signature" to be ordered prime exponents (a_0,a_1,...,a_n). Least integer with a given "mod 2 prime signature" is obtained by replacing p_1 with 3, p_2 with 5,..., p_n with n-th odd prime. LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(n) = A006519(n)*A003961(A046523(A000265(n))). - Antti Karttunen, Sep 27 2018 PROG (PARI) A000265(n) = (n/2^valuation(n, 2)); A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961 A006519(n) = (1<

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Last modified January 26 13:42 EST 2022. Contains 350598 sequences. (Running on oeis4.)