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 A119456 Numbers m such that the Bernoulli number B_{10*m} has denominator 66. 30
 1, 5, 17, 37, 47, 59, 61, 67, 71, 73, 79, 85, 101, 107, 127, 137, 139, 149, 163, 167, 185, 197, 199, 223, 227, 229, 257, 263, 269, 277, 283, 289, 295, 305, 307, 311, 313, 317, 331, 335, 347, 353, 355, 365, 373, 379, 383, 389, 395, 397, 401, 433, 449, 457, 461 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Subset of A002181 (inverse of the Euler totient function). Most terms are primes except for n = 12, 21, 32, 33, 34, 40, ... because a(12) = 85 = 5*17, a(21) = 185 = 5*37, a(32) = 289 = 17*17, a(33) = 295 = 5*59, a(34) = 305 = 5*61, a(40) = 335 = 5*67, ... Each composite term appears to be a product of two primes from previous terms or a square of a prime from previous terms. Composite terms are the products of powers of primes that are factors of previous terms. For example, there are terms equal to 17, 17^2, 5*17^2, 59^2, 59*61, 61^2, 61*67, 67^2, 67*73, 17^3, 5*17*59, 71*73, 5*17*61, 73^2, 71*79, 73*79, 5*17*73, 79^2, 61*167, 101^2, 37*277, 5*37*59, 79*139, 107^2, 5*17*139, 5*37*67, 5*37*71, 17^2*47, 61*223, 61*227, 5*17*163, 5*17*167, 71*227, 127^2, 17^2*59, 5*59^2, 17^2*61, 5*61^2, 137^2, 137*139, 139^2, 17^2*67, 5*17*229, 137*149, 5*61*67, 5*59*71, 17^2*73, 5*67^2, 5*61*79, 5*67*73, 5*17^3, ... - Alexander Adamchuk, Jul 28 2006 LINKS E. PĂ©rez Herrero, Table of n, a(n) for n=1..50000 FORMULA a(n) = A051230(n)/10 = A051229(n)/5. MATHEMATICA Do[s=1+Divisors[n]; s1=Flatten[Position[PrimeQ[s], True]]; s2=Part[s, s1]; If[Equal[s2, {2, 3, 11}], Print[n/10]], {n, 1, 50000}] - Alexander Adamchuk, Jul 28 2006 CROSSREFS Cf. A002181, A002445, A051229, A051230. Sequence in context: A321658 A080167 A060245 * A264904 A257582 A339988 Adjacent sequences:  A119453 A119454 A119455 * A119457 A119458 A119459 KEYWORD nonn AUTHOR Alexander Adamchuk, Jul 26 2006 EXTENSIONS More terms from Alexander Adamchuk, Jul 28 2006 STATUS approved

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Last modified January 27 14:44 EST 2022. Contains 350607 sequences. (Running on oeis4.)