A102115 -id:A102115 - cp's OEIS frontend

A102195 Iccanobirt semiprimes (5 of 15): Semiprime numbers in A102115.

4, 779, 1138, 57415, 77633, 55486847, 1073911003, 3317721397, 1060433508262511, 71024113009688593314067, 11974445409544006175987023, 1076202964567631961558639609002933, 33696092853645518103687453241761538, 4617443279524324394317910914689160360213

Offset: 1

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Harvey P. Dale, Table of n, a(n) for n = 1..19

Cf. A001358, A102115, A102191-A102205.

nxt[{a_,b_,c_}]:={b,c,Total[FromDigits/@Reverse/@IntegerDigits[{a,c}]]+b};Select[NestList[nxt,{0,0,1},120][[;;,1]],PrimeOmega[#]==2&] (* Harvey P. Dale, Mar 02 2025 *)

a(n) = A102115(A102175(n)).

Offset changed to 1 and a(14) from Jinyuan Wang, Aug 12 2021

A102135 Iccanobirt prime indices (5 of 15): Indices of prime numbers in A102115.

Original entry on oeis.org

4, 6, 7, 19, 46, 613, 1146, 1500, 1982, 2590, 7278, 13714, 15929

Offset: 1

Jonathan Vos Post and Ray Chandler, Dec 31 2004

No more terms through 5000.

a(14) > 50000. - Robert Price, Nov 08 2018

Cf. A000040, A102115, A102131-A102145.

a[n_] := a[n] =
   IntegerReverse[a[n - 1]] + a[n - 2] + IntegerReverse[a[n - 3]];
a[0] = 0; a[1] = 0; a[2] = 1;
Select[Range[0, 5000], PrimeQ[a[#]] &] (* Robert Price, Apr 10 2020 *)
nxt[{a_,b_,c_}]:={b,c,Total[IntegerReverse[{a,c}]]+b};Flatten[Position[NestList[nxt,{0,0,1},2600][[;;,1]],?PrimeQ]]-1 (* The program generates the first 10 terms of the sequence. *) (* _Harvey P. Dale, Oct 23 2024 *)

A102115(a(n)) = A102155(n).

a(11)-a(13) from Robert Price, Nov 08 2018

A102155 Iccanobirt primes (5 of 15): Prime numbers in A102115.

Original entry on oeis.org

2, 7, 13, 541549, 6058778554555591

Offset: 1

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Next term is too large to include.

Cf. A000040, A102115, A102151-A102165.

a(n) = A102115(A102135(n)).

Offset changed to 1 by Jinyuan Wang, Aug 12 2021

A102175 Iccanobirt semiprime indices (5 of 15): Indices of semiprime numbers in A102115.

Original entry on oeis.org

5, 11, 12, 16, 17, 24, 28, 29, 43, 64, 70, 89, 94, 109, 134, 136, 138, 158, 194, 219, 316

Offset: 1

Jonathan Vos Post and Ray Chandler, Dec 31 2004

Cf. A001358, A102115, A102171-A102185, A102195.

A102115(a(n)) = A102195(n).

a(20) from Robert Price, Nov 08 2018

Offset changed to 1 and a(21) from Jinyuan Wang, Aug 12 2021

A102123 Iccanobirt numbers (13 of 15): a(n) = R(R(a(n-1)) + a(n-2) + R(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, 711, 761, 49, 279, 8811, 1651, 44311, 38141, 55006, 45901, 34108, 990681, 161132, 5891031, 6129461, 8041777, 45820251, 74839842, 60558487, 202825861, 635089352, 309192535, 7549098331, 8252802091

Offset: 0

Jonathan Vos Post and Ray Chandler, Dec 30 2004

Digit reversal variation of tribonacci numbers A000073.

Inspired by Iccanobif numbers: A001129, A014258-A014260.

Cf. A102111-A102125.

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]+R[a[n-3]]];Table[a[n], {n, 0, 40}]

a(n) = A004086(A102115(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

Jonathan Vos Post and Ray Chandler, Dec 30 2004

Digit reversal variation of tribonacci numbers A000073.

Inspired by Iccanobif numbers: A001129, A014258-A014260.

Harvey P. Dale, Table of n, a(n) for n = 0..1000

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

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 *)

Incorrect formula removed by Georg Fischer, Dec 18 2020

cp's OEIS Frontend

A102195 Iccanobirt semiprimes (5 of 15): Semiprime numbers in A102115.

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A102135 Iccanobirt prime indices (5 of 15): Indices of prime numbers in A102115.

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A102155 Iccanobirt primes (5 of 15): Prime numbers in A102115.

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A102175 Iccanobirt semiprime indices (5 of 15): Indices of semiprime numbers in A102115.

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A102123 Iccanobirt numbers (13 of 15): a(n) = R(R(a(n-1)) + a(n-2) + R(a(n-3))), where R is the digit reversal function A004086.

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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.

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