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.

A349028 Lucas-Carmichael numbers with 9 prime factors.

Original entry on oeis.org

14563696180319, 16569718534655, 20203946790335, 22034564147519, 23315834862719, 23889526894079, 27074874805055, 28932092649215, 31534433588735, 34236981827279, 34249223161439, 45373136257295, 45593377151399, 50103079391519, 50415330959279, 50683388926247
Offset: 1

Views

Author

Tim Johannes Ohrtmann, Nov 06 2021

Keywords

Examples

			14563696180319 = 11*13*17*23*29*41*47*59*79 and 12, 14, 18, 24, 30, 42, 48, 60, and 80 all divide 14563696180320.

Links

Crossrefs

Intersection of A006972 and A046312.
Cf. A216928 (least Lucas-Carmichael number with n prime factors).
Cf. A216925, A216926, A216927, A217002, A217003, A217091, A349029, A349030 (Lucas-Carmichael numbers with 3-8, 10 and 11 prime factors).

Programs

  • PARI
    is(n)={omega(n)==9&&is_A006972(n)}

A349029 Lucas-Carmichael numbers with 10 prime factors.

Original entry on oeis.org

989565001538399, 1250312791224959, 1419432982021439, 1518134614712639, 2240225337903839, 2493922560242399, 2708548708646879, 2786001880066559, 2807577905060159, 2808521396058455, 3157015238986895, 3210972445532159, 3221015190555239, 3407706183722399, 3614740529402519
Offset: 1

Views

Author

Tim Johannes Ohrtmann, Nov 06 2021

Keywords

Examples

			989565001538399 = 11*13*17*19*29*31*41*47*83*149 and 12, 14, 18, 20, 30, 32, 42, 48, 84, and 150 all divide 989565001538400.

Links

Crossrefs

Intersection of A006972 and A046314.
Cf. A216928 (least Lucas-Carmichael number with n prime factors).
Cf. A216925, A216926, A216927, A217002, A217003, A217091, A349028, A349030 (Lucas-Carmichael numbers with 3-9 and 11 prime factors).

Programs

  • PARI
    is(n)={omega(n)==10&&is_A006972(n)}

A349030 Lucas-Carmichael numbers with 11 prime factors.

Original entry on oeis.org

20576473996736735, 42380075646230399, 75943207554554879, 83668951228080959, 96195222056687039, 116436396482735615, 132525862783734959, 134052021887096159, 162544912900261199, 175900784368936319, 186326804496197519, 190523141606006495, 196467189590024639
Offset: 1

Views

Author

Tim Johannes Ohrtmann, Nov 06 2021

Keywords

Examples

			20576473996736735 = 5*7*11*17*23*31*47*53*71*107*233 and 6, 8, 12, 18, 24, 32, 48, 54, 72, 108, and 234 all divide 20576473996736736.

Links

Crossrefs

Intersection of A006972 and A069272.
Cf. A216928 (least Lucas-Carmichael number with n prime factors).
Cf. A216925, A216926, A216927, A217002, A217003, A217091, A349028, A349029 (Lucas-Carmichael numbers with 3-10 prime factors).

Programs

  • PARI
    is(n)={omega(n)==11&&is_A006972(n)}

A300959 Number of prime factors of the n-th Lucas-Carmichael number.

Original entry on oeis.org

3, 3, 3, 3, 3, 3, 3, 4, 3, 4, 3, 3, 3, 4, 4, 3, 4, 3, 3, 3, 4, 3, 3, 4, 3, 3, 3, 4, 3, 4, 3, 3, 4, 4, 4, 3, 3, 4, 3, 4, 4, 3, 4, 3, 5, 4, 3, 3, 3, 3, 4, 3, 3, 4, 3, 4, 4, 3, 3, 3, 5, 4, 4, 3, 3, 4, 3, 4, 3, 3, 4, 4, 4, 3, 3, 4, 4, 3, 4, 4, 4, 4, 3, 5, 3, 4, 3
Offset: 1

Views

Author

Tim Johannes Ohrtmann, Mar 17 2018

Keywords

Comments

The number of prime factors is always >= 3.

Links

Crossrefs

Cf. A006972 (Lucas-Carmichael numbers).
Cf. A216925, A216926, A216927, A217002, A217003, A217091 (Lucas-Carmichael numbers with 3 to 8 prime factors).
Cf. A216928 (Least Lucas-Carmichael number with n prime factors).

Programs

  • PARI
    islc(n)=my(f=factor(n)); for(i=1, #f[, 1], if((n+1)%(f[i, 1]+1) || f[i, 2]>1, return(0))); #f[, 1]>1; \\ from A006972
lista(nn) = for (n=1, nn, if (islc(n), print1(omega(n), ", "))); \\ Michel Marcus, Mar 17 2018

Formula

a(n) = A001221(A006972(n)).
Showing 1-4 of 4 results.

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