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.

Showing 1-2 of 2 results.

A377876 The n-th primorial number reduced modulo 27.

Original entry on oeis.org

1, 2, 6, 3, 21, 15, 6, 21, 21, 24, 21, 3, 3, 15, 24, 21, 6, 3, 21, 3, 24, 24, 6, 12, 15, 24, 21, 3, 24, 24, 12, 12, 6, 12, 21, 24, 6, 24, 24, 12, 24, 3, 3, 6, 24, 3, 3, 12, 3, 6, 24, 3, 15, 24, 3, 15, 3, 24, 24, 6, 12, 21, 24, 24, 12, 3, 6, 15, 6, 3, 21, 15, 12, 3, 12, 12, 6, 12, 12, 6, 24, 12, 3, 24, 24, 6, 12, 15
Offset: 0

Views

Author

Antti Karttunen, Nov 12 2024

Keywords

Links

Crossrefs

Cf. A002110, A377872.
Cf. also A086360, A377877.

Programs

  • Maple
    R:= 1: p:= 1: v:= 1:
for i from 1 to 100 do
  p:= nextprime(p); v:= p*v mod 27;
  R:= R,v;
od:
R; # Robert Israel, Nov 12 2024
  • Mathematica
    Mod[FoldList[Times,1,Prime[Range[87]]],27] (* James C. McMahon, Nov 12 2024 *)
  • PARI
    A002110(n) = prod(i=1,n,prime(i));
A377876(n) = (A002110(n)%27);
  • PARI
    up_to = 105;
A377876list(up_to_n) = { my(m=27, v=vector(1+up_to_n), pr=1); v[1] = 1; for(n=1, up_to_n, pr *= Mod(prime(n),m); v[1+n] = lift(pr)); (v); };
v377876 = A377876list(up_to);
A377876(n) = v377876[1+n];
  • Python
    from functools import reduce
from sympy import primerange, prime
def A377876(n): return reduce(lambda x,y:x*y%27,primerange(prime(n)+1)) if n else 1 # Chai Wah Wu, Nov 12 2024

Formula

a(n) = A002110(n) mod 27.

A377877 The n-th primorial number reduced modulo 3125.

Original entry on oeis.org

1, 2, 6, 30, 210, 2310, 1905, 1135, 2815, 2245, 2605, 2630, 435, 2210, 1280, 785, 980, 1570, 2020, 965, 2890, 1595, 1005, 2165, 2060, 2945, 570, 2460, 720, 355, 2615, 855, 2630, 935, 1840, 2285, 1285, 1745, 60, 645, 2210, 1840, 1790, 1265, 395, 2815, 810, 2160, 430, 735, 2690, 1770, 1155, 230, 1480, 2235, 305, 795
Offset: 0

Views

Author

Antti Karttunen, Nov 13 2024

Keywords

Links

Crossrefs

Cf. A002110.
Cf. also A086360, A377876.

Programs

  • Mathematica
    Mod[FoldList[Times, 1, Prime[Range[100]]], 3125] (* Paolo Xausa, Nov 13 2024 *)
  • PARI
    A002110(n) = prod(i=1,n,prime(i));
A377877(n) = (A002110(n)%3125);
  • PARI
    up_to = 15625;
A377877list(up_to_n) = { my(m=5^5, v=vector(1+up_to_n), pr=1); v[1] = 1; for(n=1, up_to_n, pr *= Mod(prime(n),m); v[1+n] = lift(pr)); (v); };
v377877 = A377877list(up_to);
A377877(n) = v377877[1+n];

Formula

a(n) = A002110(n) mod (5^5).
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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