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 1-6 of 6 results.

A102134 Iccanobirt prime indices (4 of 15): Indices of prime numbers in A102114.

Original entry on oeis.org

4, 6, 7, 22, 32, 48, 58, 61, 80, 85, 119, 136, 150, 184, 420, 591, 878, 2447, 30938
Offset: 1

Views

Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Keywords

Comments

No more terms through 5000.
No more terms through 7500. From Harvey P. Dale, May 30 2012
a(20) > 50000. - Robert Price, Nov 08 2018

Crossrefs

Cf. A000040, A102114, A102131-A102145.

Programs

  • Mathematica
    nxt[{a_,b_,c_}]:={b,c,FromDigits[Reverse[IntegerDigits[c]]]+b+a}; Flatten[ Position[Transpose[NestList[nxt,{0,0,1},2500]][[1]],?PrimeQ]-1] (* _Harvey P. Dale, May 30 2012 *)

Formula

A102114(a(n)) = A102154(n).

Extensions

a(19) from Robert Price, Nov 08 2018

A102154 Iccanobirt primes (4 of 15): Prime numbers in A102114.

Original entry on oeis.org

2, 7, 13, 823541, 131622637, 42562230754481, 81409990081365019, 854720149266848129, 10368894671263026260137261, 462512205427594928694039517, 2554464709394644494293414485734745657, 10316628799362671595219100337312778857284159, 124041034096767708661687005571699720680324204493
Offset: 1

Views

Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Keywords

Crossrefs

Cf. A000040, A102114, A102151-A102165.

Programs

  • Mathematica
    nxt[{a_, b_, c_}] := {b, c, IntegerReverse[c] + b + a}; Select[ NestList[ nxt, {0, 0, 1}, 400][[ All, 1]], PrimeQ] (* Harvey P. Dale, Apr 14 2022 *)

Formula

a(n) = A102114(A102134(n)).

Extensions

Offset changed to 1 and more terms from Jinyuan Wang, Aug 10 2021

A102174 Iccanobirt semiprime indices (4 of 15): Indices of semiprime numbers in A102114.

Original entry on oeis.org

5, 11, 18, 33, 35, 37, 43, 44, 56, 63, 93, 148, 175, 176, 204, 288, 317
Offset: 1

Views

Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Keywords

Crossrefs

Cf. A001358, A102114, A102171-A102185, A102194.

Programs

Formula

A102114(a(n)) = A102194(n).

Extensions

a(15) from Robert Price, Nov 08 2018
Offset changed to 1 and a(16)-a(17) from Jinyuan Wang, Aug 10 2021

A102194 Iccanobirt semiprimes (4 of 15): Semiprime numbers in A102114.

Original entry on oeis.org

4, 185, 24361, 921717757, 1920600983, 9086150726, 913083071429, 2014396919113, 63178492261555241, 9004315140856495091, 63162327910155025982578333897, 27030665951900873389459251276162714636270614605, 71854905634496924458553731195035575408569457647039865953
Offset: 1

Views

Author

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Keywords

Crossrefs

Cf. A001358, A102114, A102191-A102205.

Formula

a(n) = A102114(A102174(n)).

Extensions

Offset changed to 1 and a(13) from Jinyuan Wang, Aug 10 2021

A102122 Iccanobirt numbers (12 of 15): a(n) = R(R(a(n-1)) + a(n-2) + a(n-3)), where R is the digit reversal function A004086.

Original entry on oeis.org

0, 0, 1, 1, 2, 4, 7, 31, 42, 26, 531, 302, 67, 909, 8721, 4522, 48811, 72152, 6487, 908821, 844702, 6572211, 9726782, 29139201, 58129562, 86185456, 139627251, 949140792, 656458225, 9962261161, 6171227123, 20114953831, 68392496992
Offset: 0

Views

Author

Jonathan Vos Post and Ray Chandler, Dec 30 2004

Keywords

Comments

Digit reversal variation of tribonacci numbers A000073.
Inspired by Iccanobif numbers: A001129, A014258-A014260.

Crossrefs

Cf. A102111-A102125.

Programs

  • Mathematica
    R[n_]:=FromDigits[Reverse[IntegerDigits[n]]];Clear[a];a[0]=0;a[1]=0;a[2]=1;a [n_]:=a[n]=R[R[a[n-1]]+a[n-2]+a[n-3]];Table[a[n], {n, 0, 40}]
nxt[{a_,b_,c_}]:={b,c,IntegerReverse[IntegerReverse[c]+b+a]}; NestList[nxt,{0,0,1},40][[;;,1]] (* Harvey P. Dale, Sep 10 2024 *)

Formula

a(n) = A004086(A102114(n)).

A102118 Iccanobirt numbers (8 of 15): a(n) = R(a(n-1) + a(n-2) + a(n-3)), where R is the digit reversal function A004086.

Original entry on oeis.org

0, 0, 1, 1, 2, 4, 7, 31, 24, 26, 18, 86, 31, 531, 846, 8041, 8149, 63071, 16297, 71578, 649051, 629637, 6620531, 9129987, 55108361, 97885807, 551421261, 924514407, 5741283751, 9149127127, 58252941851, 92725334137, 511304721061
Offset: 0

Views

Author

Jonathan Vos Post and Ray Chandler, Dec 30 2004

Keywords

Comments

Digit reversal variation of tribonacci numbers A000073.
Inspired by Iccanobif numbers: A001129, A014258-A014260.

Links

Crossrefs

Cf. A102111, A102112, A102113, A102114, A102115, A102116, A102117, A102119, A102120, A102121, A102122, A102123, A102124, A102125.

Programs

  • Mathematica
    R[n_]:=FromDigits[Reverse[IntegerDigits[n]]];Clear[a];a[0]=0;a[1]=0;a[2]=1;a [n_]:=a[n]=R[a[n-1]+a[n-2]+a[n-3]];Table[a[n], {n, 0, 40}]
Transpose[NestList[{#[[2]],#[[3]],FromDigits[Reverse[IntegerDigits[Total[ #]]]]}&,{0,0,1},40]][[1]] (* Harvey P. Dale, Dec 04 2012 *)

Extensions

Incorrect formula removed by Georg Fischer, Dec 18 2020
Showing 1-6 of 6 results.

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

Content is available under The OEIS End-User License Agreement.