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 1-4 of 4 results.

A354609 Carmichael numbers ending in 1.

Original entry on oeis.org

561, 2821, 6601, 8911, 15841, 29341, 41041, 75361, 101101, 115921, 162401, 172081, 188461, 252601, 314821, 340561, 399001, 410041, 488881, 512461, 530881, 552721, 656601, 658801, 838201, 852841, 1024651, 1152271, 1193221, 1461241, 1615681, 1857241, 1909001, 2100901, 2113921, 2433601, 2455921, 2704801, 3057601
Offset: 1

Views

Author

Omar E. Pol, Jul 08 2022

Keywords

Links

Crossrefs

Intersection of A002997 and A017281.
Cf. A352970, A355305, A355307, A355309.

Programs

  • Mathematica
    Select[10*Range[0, 3*10^5] + 1, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* Amiram Eldar, Jul 08 2022 *)
  • Python
    from itertools import islice
from sympy import nextprime, factorint
def A354609_gen(): # generator of terms
    p, q = 3, 5
    while True:
        for n in range(p+2+(-p-1)%10, q, 10):
            f = factorint(n)
            if max(f.values()) == 1 and not any((n-1) % (p-1) for p in f):
                yield n
        p, q = q, nextprime(q)
A354609_list = list(islice(A354609_gen(),30)) # Chai Wah Wu, Jul 24 2022

A355305 Carmichael numbers ending in 5.

Original entry on oeis.org

1105, 2465, 10585, 62745, 278545, 449065, 825265, 1050985, 2531845, 3224065, 3664585, 5632705, 6054985, 9582145, 11119105, 12945745, 13187665, 13992265, 15403285, 21584305, 22665505, 28787185, 31692805, 36121345, 37354465, 39353665, 40280065, 41298985, 47006785, 60112885, 67371265, 74165065, 84417985
Offset: 1

Views

Author

Omar E. Pol, Jul 03 2022

Keywords

Links

Crossrefs

Intersection of A002997 and A017329.
Cf. A352970, A354609, A355307, A355309.

Programs

  • Mathematica
    Select[10*Range[0, 10^7] + 5, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* Amiram Eldar, Jul 07 2022 *)
  • PARI
    Korselt(n) = my(f=factor(n)); for(i=1, #f[, 1], if(f[i, 2]>1||(n-1)%(f[i, 1]-1), return(0))); 1;
isok(n) = ((n%10)==5) && !isprime(n) && Korselt(n) && n>1; \\ Michel Marcus, Jul 07 2022; after A002997
  • Python
    from itertools import islice
from sympy import factorint, nextprime
def A355305_gen(): # generator of terms
    p, q = 3, 5
    while True:
        for n in range(p+2+(-p+3)%10, q, 10):
            f = factorint(n)
            if max(f.values()) == 1 and not any((n-1) % (p-1) for p in f):
                yield n
        p, q = q, nextprime(q)
A355305_list = list(islice(A355305_gen(),10)) # Chai Wah Wu, Jul 24 2022

A355307 Carmichael numbers ending in 7.

Original entry on oeis.org

46657, 126217, 748657, 1569457, 4909177, 9613297, 11972017, 40160737, 55462177, 65037817, 106041937, 161035057, 178451857, 193910977, 196358977, 311388337, 328573477, 338740417, 358940737, 403043257, 461502097, 499310197, 556450777, 569332177, 633639097, 784966297, 902645857, 981789337, 1125038377
Offset: 1

Views

Author

Omar E. Pol, Jul 24 2022

Keywords

Links

Crossrefs

Intersection of A002997 and A017353.
Cf. A352970, A354609, A355305, A355309.

Programs

  • Mathematica
    Select[10*Range[0, 10^7] + 7, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* Amiram Eldar, Jul 24 2022 *)
  • Python
    from itertools import count, islice
from sympy import factorint
def A355307_gen(): # generator of terms
    for n in count(7,10):
        f = factorint(n)
        if len(f) == sum(f.values()) > 1 and not any((n-1) % (p-1) for p in f):
            yield n
A355307_list = list(islice(A355307_gen(),5)) # Chai Wah Wu, Jul 25 2022

A355309 Carmichael numbers ending in 3.

Original entry on oeis.org

52633, 63973, 334153, 670033, 997633, 2508013, 2628073, 5968873, 6733693, 13696033, 15829633, 15888313, 18900973, 26280073, 27336673, 46483633, 53711113, 65241793, 67653433, 75765313, 124630273, 133344793, 158864833, 182356993, 227752993, 242641153, 292244833, 426821473, 577240273, 580565233, 600892993
Offset: 1

Views

Author

Omar E. Pol, Jul 25 2022

Keywords

Links

Crossrefs

Intersection of A002997 and A017305.
Cf. A352970, A354609, A355305, A355307.

Programs

  • Mathematica
    Select[10*Range[0, 10^7] + 3, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* Amiram Eldar, Jul 25 2022 *)
  • Python
    from itertools import count, islice
from sympy import factorint
def A355309_gen(): # generator of terms
    for n in count(3,10):
        f = factorint(n)
        if len(f) == sum(f.values()) > 1 and not any((n-1) % (p-1) for p in f):
            yield n
A355309_list = list(islice(A355309_gen(),5)) # Chai Wah Wu, Jul 26 2022
Showing 1-4 of 4 results.

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

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