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 A342012 Primorial deflation of the n-th colossally abundant number: the unique integer k such that A108951(k) = A004490(n). 7
 2, 3, 6, 10, 20, 30, 42, 84, 132, 156, 312, 468, 780, 1020, 1140, 1380, 2760, 3480, 3720, 5208, 7812, 9324, 10332, 10836, 21672, 23688, 26712, 29736, 49560, 51240, 56280, 59640, 61320, 96360, 104280, 208560, 219120, 328680, 352440, 384120, 453960, 472680, 482040, 500760, 510120, 528840, 594360, 613080, 641160, 650520, 1301040 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS In contrast to A329902, this sequence is monotonic, because each term is obtained from the previous, either by multiplying it by 2, or by "bumping" one [or hypothetically: two] of its prime factors one step up (i.e., replacing it with the next larger prime), and both operations are guaranteed to make the number larger. LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A319626(A004490(n)) = A329900(A004490(n)). a(n) = A005940(1+A342013(n)). PROG (PARI) v073751 = readvec("b073751_to.txt"); A073751(n) = v073751[n]; A004490list(v073751) = { my(v=vector(#v073751)); v[1] = 2; for(n=2, #v, v[n] = v073751[n]*v[n-1]); (v); }; v004490 = A004490list(v073751); A004490(n) = v004490[n]; A064989(n) = {my(f); f = factor(n); if((n>1 && f[1, 1]==2), f[1, 2] = 0); for (i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f)}; A319626(n) = (n / gcd(n, A064989(n))); A342012(n) = A319626(A004490(n)); CROSSREFS Cf. A004490, A005940, A073751, A108951, A319626, A329900, A342010 [= A001222(a(n))], A342011, A342013. Cf. also A217867, A329902. Sequence in context: A001678 A346787 A113292 * A050291 A324739 A214002 Adjacent sequences: A342009 A342010 A342011 * A342013 A342014 A342015 KEYWORD nonn AUTHOR Antti Karttunen, Mar 08 2021 STATUS approved

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Last modified June 23 01:45 EDT 2024. Contains 373629 sequences. (Running on oeis4.)