cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A350641 Numbers k such that the product of k and all terms < k in A050376 has more divisors than the product of all terms < k in A050376 and the smallest term > k in A050376.

Original entry on oeis.org

42, 66, 72, 78, 88, 104, 110, 130, 136, 152, 156, 160, 170, 184, 190, 200, 204, 224, 228, 230, 232, 238, 240, 248, 255, 285, 345, 435, 460, 465, 483, 525, 555, 580, 600, 609, 615, 620, 651, 696, 744, 777, 783, 812, 837, 861, 868, 888, 903, 930, 984, 987, 999
Offset: 1

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Author

J. Lowell, Jan 09 2022

Keywords

Comments

Multiplying a number in this sequence by all numbers in A050376 less than it will give a number less than, but with more divisors than, a number in A037992 with comparable magnitude.

Examples

			The product of 42 and all terms < 42 in A050376 has 276480 divisors. The product of all terms < 42 in A050376 and the smallest term > 42 (i.e., 43) in A050376 has only 262144 divisors. Thus, 42 is a term of this sequence.
		

Crossrefs

Programs

  • PARI
    list(lim) = my(v=primes(primepi(lim)), t); forprime(p=2, sqrt(lim), t=p; while((t=t^2)<=lim, v=concat(v, t))); vecsort(v); \\ A050376
    lista(nn) = my(vfd=list(nn), res=List()); for (n=1, nn, my(vless = select(x->(x(x>n), vfd)); if (#vmore, my(p = vecprod(vless)); if (numdiv(p*n) > numdiv(p*vmore[1]), listput(res, n));););); res; \\ Michel Marcus, Jan 10 2022

Extensions

More terms from Jinyuan Wang, Jan 09 2022