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.

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A282424 Semiprimes p such that next semiprime after p is p + 50.

Original entry on oeis.org

1226777, 4732631, 5093729, 9210671, 12515461, 12917989, 16121409, 16183253, 16698881, 17263069, 19418903, 23003807, 24534161, 26519563, 26726659, 27625067, 29605299, 29772471, 32655031, 34027277, 34366179, 35340719, 37570683, 38117319, 38687461, 39038399, 39479381
Offset: 1

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Author

Zak Seidov, Feb 14 2017

Keywords

Comments

All terms are odd because even semiprime 2*p plus 50 = 2*(p+25) is multiple of 4 and not semiprime.
Note that a(1) = 1226777 = A131109(50).
Smallest possible difference is 50 but among first 10000 terms
the least difference 100 is between a(325) = 228601303 and a(326) = 228601403.

Links

Crossrefs

Cf. A001358, A131109, A217030, A217335, A217357, A282407.

Programs

  • PARI
    lista(nn) = my(r); for(k=1, nn, if(bigomega(k)==2, if(k-r==50, print1(r, ", ")); r=k)); \\ Jinyuan Wang, May 23 2021
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