A153077
Largest number m such that sigma(m) = A002110(n) where A002110(n) is the product of the first n primes.
Original entry on oeis.org
5, 29, 116, 2309, 30029, 272264, 6715161, 154448901, 3696967556, 126321788241, 5984466237725, 304250263527209, 7475863618097156, 495878856926202725, 17521052944725830450, 1749278213298193453469, 65483587607609351045025
Offset: 2
a(9) = 154448901. Sigma(154448901) = A002110(9) = 223092870 = 2*3*5*7*11*13*17*19*23.
A153078
Number of values of m such that sigma(m) = A002110(n) where A002110(n) is the product of the first n primes.
Original entry on oeis.org
0, 1, 1, 2, 2, 5, 2, 4, 5, 3, 7, 5, 10, 2, 8, 4, 5, 6, 11, 32, 42, 68, 24, 87
Offset: 1
a(10) = 3 because 2388809736, 3450503048 and 3696967556 are the only numbers with a sigma value = A002110(10). A002110(10) = 6469693230 = 2*3*5*7*11*13*17*19*23*29.
A152562
Smallest number m such that sigma(m) has exactly n distinct prime factors.
Original entry on oeis.org
2, 5, 20, 104, 936, 13842, 188424, 3249576, 81239400, 2388809736, 59720243400
Offset: 1
a(9) = 81239400; sigma(81239400) = 300690390 = 2*3*5*7*11*13*17*19*31 (9 distinct prime factors).
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v=vector(9); for(m=2, 81239400, n=omega(sigma(m)); if(v[n]==0, v[n]=m; print(n " " v[n]))) /* Donovan Johnson, Mar 31 2013 */
A291373
a(n) is the smallest number k such that A001065(k) = A002110(n), or 0 if no such k exists.
Original entry on oeis.org
2, 0, 6, 841, 0, 1722, 30018, 0, 0, 0, 4057230930, 0, 0, 92568222856376123089883329681
Offset: 0
a(5) = 1722 because sigma(1722) - 1722 = 2*3*5*7*11 = A002110(5) and 1722 is the least number with this property.
Cf.
A001065,
A002110,
A057704,
A070015,
A116017,
A153076,
A235710,
A244444,
A279359,
A291356,
A378099.
Showing 1-4 of 4 results.
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