Sergei D. Shchebetov - cp's OEIS frontend

A353185 Numbers which require exactly 289 'Reverse and Add' steps to reach a palindrome.

10037000230509917799950, 10037000240508917799950, 10037000250507917799950, 10037000260506917799950, 10037000270505917799950, 10037000280504917799950, 10037000290503917799950, 10037000330509817799950, 10037000340508817799950

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Apr 29 2022

The sequence starts with 10037000230509917799950, ends with 15999771990503200073000 and contains 9031680 terms known at present, including 13968441660506503386020 and 13568441660506503386420 discovered by Anton Stefanov on January 5, 2021.

Popular Computing (Calabasas, CA), The 196 Problem, Vol. 3 (No. 30, Sep 1975).

Sergei D. Shchebetov, Table of n, a(n) for n = 1..10000
Jason Doucette, World Records
Yutaka Nishiyama, Numerical Palindromes and the 196 Problem, International Journal of Pure and Applied Mathematics, Volume 80, No. 3, 2012, 375-384.
Sergei D. Shchebetov, 9031680 terms (zipped file)
R. Styer, The Palindromic Conjecture and the Fibonacci Sequence, Villanova University, 1986, 1-11.
C. W. Trigg, Palindromes by Addition, Mathematics Magazine, 40 (1967), 26-28.
C. W. Trigg, More on Palindromes by Reversal-Addition, Mathematics Magazine, 45 (1972), 184-186.
Wikipedia, Lychrel Number
196 and Other Lychrel Numbers, 196 and Lychrel Number
Index entries for sequences related to Reverse and Add!

A023109, A033672, A065198, A065199, A065320, A065321, A065322, A065323, A065324, A065325, A065326, A065327, A070743, A072216, A072217, A072218, A281301, A281390, A281506, A281507, A326414.

Each term requires exactly 289 steps to turn into a 142-digit palindrome.

A326414 Numbers which require exactly 288 'Reverse and Add' steps to reach a palindrome.

Original entry on oeis.org

12000700000025339936491, 12000700001015339936491, 12000700002005339936491, 12000700010024339936491, 12000700011014339936491, 12000700012004339936491, 12000700020023339936491, 12000700021013339936491, 12000700022003339936491, 12000700030022339936491

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Oct 18 2019

Popular Computing (Calabasas, CA), The 196 Problem, Vol. 3 (No. 30, Sep 1975).

Sergei D. Shchebetov, Table of n, a(n) for n = 1..10000
Jason Doucette, World Records
Yutaka Nishiyama, Numerical Palindromes and the 196 Problem, International Journal of Pure and Applied Mathematics, Volume 80, No. 3, 2012, 375-384.
Sergei D. Shchebetov, 19353600 terms (zipped file)
R. Styer, The Palindromic Conjecture and the Fibonacci Sequence, Villanova University, 1986, 1-11.
C. W. Trigg, Palindromes by Addition, Mathematics Magazine, 40 (1967), 26-28.
C. W. Trigg, More on Palindromes by Reversal-Addition, Mathematics Magazine, 45 (1972), 184-186.
Wikipedia, Lychrel Number
196 and Other Lychrel Numbers, 196 and Lychrel Number
Index entries for sequences related to Reverse and Add!

Cf. A023109, A033672, A065198, A065199, A065320, A065321, A065322, A065323, A065324, A065325, A065326, A065327, A070743, A072216, A072217, A072218, A281301, A281390, A281506, A281507.

Each term requires exactly 288 steps to turn into a 142-digit palindrome.

Deleted an erroneous comment that said that the sequence was finite. - N. J. A. Sloane, Jun 23 2022

A298821 Primes p for which pi_{24,19}(p) - pi_{24,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

706866045116113, 706866045126361, 706866045126697, 706866045126907, 706866045128377, 706866045128563, 706866045128953, 706866045129163, 706866045129403, 706866045130057, 706866045130153, 706866045130459, 706866045130723, 706866045130771, 706866045131107, 706866045155113, 706866045155899, 706866045156043, 706866045156409, 706866045156499

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Jan 27 2018

nonn

This is a companion sequence to A298820 and the first discovered for pi_{24,19}(p) - pi_{24,1}(p) prime race. The full sequence up to 10^15 contains 5 sign-changing zones with 3436990 terms in total with A(3436990) = 766164822666883 as the last one.

Andrey S. Shchebetov and Sergei D. Shchebetov, Table of n, a(n) for n = 1..100000
A. Granville and G. Martin, Prime Number Races, Amer. Math. Monthly 113 (2006), no. 1, 1-33.
Richard H. Hudson and Carter Bays, The appearance of tens of billion of integers x with pi_{24, 13}(x) < pi_{24, 1}(x) in the vicinity of 10^12, Journal für die reine und angewandte Mathematik, 299/300 (1978), 234-237. MR 57 #12418.
M. Rubinstein and P. Sarnak, Chebyshev’s bias, Experimental Mathematics, Volume 3, Issue 3, 1994, Pages 173-197.
Eric Weisstein's World of Mathematics, Prime Quadratic Effect.

Cf. A295355, A295356, A297449, A297450

A298820 Values of n for which pi_{24,19}(p_n) - pi_{24,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

21317046795798, 21317046796093, 21317046796102, 21317046796104, 21317046796154, 21317046796159, 21317046796172, 21317046796185, 21317046796193, 21317046796208, 21317046796212, 21317046796221, 21317046796226, 21317046796229, 21317046796240, 21317046796968, 21317046796986, 21317046796992, 21317046797002, 21317046797007

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Jan 27 2018

nonn

This is a companion sequence to A298821 and the first discovered for pi_{24,19}(p) - pi_{24,1}(p) prime race. The full sequence up to 10^15 contains 5 sign-changing zones with 3436990 terms in total with A(3436990) = 23049274819456 as the last one.

Sergei D. Shchebetov, Table of n, a(n) for n = 1..100000
A. Granville and G. Martin, Prime Number Races, Amer. Math. Monthly 113 (2006), no. 1, 1-33.
Richard H. Hudson and Carter Bays, The appearance of tens of billion of integers x with pi_{24, 13}(x) < pi_{24, 1}(x) in the vicinity of 10^12, Journal für die reine und angewandte Mathematik, 299/300 (1978), 234-237. MR 57 #12418.
M. Rubinstein and P. Sarnak, Chebyshev’s bias, Experimental Mathematics, Volume 3, Issue 3, 1994, Pages 173-197.
Eric Weisstein's World of Mathematics, Prime Quadratic Effect.

Cf. A295355, A295356, A297449, A297450

A297450 Primes p for which pi_{24,17}(p) - pi_{24,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

617139273158713, 617139273159121, 617139273159337, 617139273163729, 617139273163793, 617139273165889, 617139273166121, 617139273167057, 617139273169273, 617139273169513, 617139273169729, 617139273170137, 617139273170401, 617139273171217, 617139273206009, 617139273206993, 617139273207449, 617139273207929, 617139273208001, 617139273504913

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Jan 27 2018

nonn

This is a companion sequence to A297449 and the first discovered for pi_{24,17}(p) - pi_{24,1}(p) prime race. The full sequence up to 10^15 contains 3 sign-changing zones with 963922 terms in total with A(963922) = 772739867710897 as the last one.

Sergei D. Shchebetov, Table of n, a(n) for n = 1..100000
A. Granville and G. Martin, Prime Number Races, Amer. Math. Monthly 113 (2006), no. 1, 1-33.
Richard H. Hudson and Carter Bays, The appearance of tens of billion of integers x with pi_{24, 13}(x) < pi_{24, 1}(x) in the vicinity of 10^12, Journal für die reine und angewandte Mathematik, 299/300 (1978), 234-237. MR 57 #12418.
M. Rubinstein and P. Sarnak, Chebyshev’s bias, Experimental Mathematics, Volume 3, Issue 3, 1994, Pages 173-197.
Eric Weisstein's World of Mathematics, Prime Quadratic Effect.

Cf. A295355, A295356.

A297449 Values of n for which pi_{24,17}(p_n) - pi_{24,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

18687728175380, 18687728175387, 18687728175395, 18687728175515, 18687728175520, 18687728175587, 18687728175592, 18687728175626, 18687728175698, 18687728175707, 18687728175715, 18687728175726, 18687728175738, 18687728175762, 18687728176789, 18687728176820, 18687728176831, 18687728176844, 18687728176846, 18687728185530

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Jan 27 2018

nonn

This is a companion sequence to A297450 and the first discovered for pi_{24,17}(p) - pi_{24,1}(p) prime race. The full sequence up to 10^15 contains 3 sign-changing zones with 963922 terms in total with A(963922) = 23241097440243 as the last one.

Sergei D. Shchebetov, Table of n, a(n) for n = 1..100000
A. Granville and G. Martin, Prime Number Races, Amer. Math. Monthly 113 (2006), no. 1, 1-33.
Richard H. Hudson and Carter Bays, The appearance of tens of billion of integers x with pi_{24, 13}(x) < pi_{24, 1}(x) in the vicinity of 10^12, Journal für die reine und angewandte Mathematik, 299/300 (1978), 234-237. MR 57 #12418.
M. Rubinstein and P. Sarnak, Chebyshev’s bias, Experimental Mathematics, Volume 3, Issue 3, 1994, Pages 173-197.
Eric Weisstein's World of Mathematics, Prime Quadratic Effect.

Cf. A295355, A295356.

A297447 Values of n for which pi_{8,5}(p_n) - pi_{8,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

30733704, 30733708, 30733714, 30733726, 30733729, 30733733, 30733743, 30733762, 30733764, 30733777, 30733781, 30733796, 30733853, 30733857, 30733860, 30733866, 30733880, 30733887, 30733890, 30734262

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Dec 30 2017

nonn

This is a companion sequence to A297448. The first two sign-changing zones were discovered by Bays and Hudson back in 1979. We discovered four additional zones starting from a(22794) = 186422420112. The full sequence with all 6 zones checked up to 5*10^14 contains 664175 terms (see a-file) with a(664175) = 6097827689926 as its last term.
This sequence was checked up to 10^15 and the 7th sign-changing zone starting from a(664176) = 27830993289634 and ending with a(850232)= 27876113171315 was found. - Andrey S. Shchebetov and Sergei D. Shchebetov, Jul 28 2018
The y-coordinate of prime(a(n)) on the Cartesian grid defined in A379643 is -1. - Ya-Ping Lu, Jan 08 2025

Sergei D. Shchebetov, Table of n, a(n) for n = 1..100000
C. Bays and R. H. Hudson, Numerical and graphical description of all axis crossing regions for moduli 4 and 8 which occur before 10^12, International Journal of Mathematics and Mathematical Sciences, vol. 2, no. 1, pp. 111-119, 1979.
C. Bays, K. Ford, R. H. Hudson and M. Rubinstein, Zeros of Dirichlet L-functions near the real axis and Chebyshev's bias, J. Number Theory 87 (2001), pp.54-76.
M. Deléglise, P. Dusart, and X. Roblot, Counting Primes in Residue Classes, Mathematics of Computation, American Mathematical Society, 2004, 73 (247), pp.1565-1575.
A. Granville and G. Martin, Prime Number Races, Amer. Math. Monthly 113 (2006), no. 1, 1-33.
M. Rubinstein and P. Sarnak, Chebyshev’s bias, Experimental Mathematics, Volume 3, Issue 3, 1994, Pages 173-197.
Eric Weisstein's World of Mathematics, Prime Quadratic Effect.

Cf. A007350, A007351, A038691, A051024, A051025, A066520, A096628, A096447, A096448, A199547, A275939, A295354, A379643, A379989.

from sympy import nextprime; p, r1, r5 = 1, 0, 0
for n in range(1, 30734263):
    p = nextprime(p); r = p%8
    if r == 1: r1 += 1
    elif r == 5: r5 += 1
if r in {1, 5} and r1 == r5 + 1: print(n, end = ', ')  # Ya-Ping Lu, Jan 08 2025

A297357 Primes p for which pi_{12,7}(p) - pi_{12,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

27489101529529, 27489101529679, 27489101529727, 27489101529847, 27489101529991, 27489101530159, 27489101530699, 27489101530747, 27489101534611, 27489101535037, 27489101535229, 27489101536843, 27489101537101, 27489101537281, 27489101537761, 27489101537827, 27489101538007, 27489101538163, 27489101539591, 27489101539723

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Dec 29 2017

nonn

This is a companion sequence to A297356 and includes the first discovered sign-changing zone for pi_{12,7}(p) - pi_{12,1}(p) prime race. The full sequence checked up to 10^14 has 55596 terms (see b-file).

Sergei D. Shchebetov, Table of n, a(n) for n = 1..55596
C. Bays, K. Ford, R. H. Hudson and M. Rubinstein, Zeros of Dirichlet L-functions near the real axis and Chebyshev's bias, J. Number Theory 87 (2001), pp. 54-76.
A. Granville and G. Martin, Prime Number Races, Amer. Math. Monthly 113 (2006), no. 1, 1-33.
M. Rubinstein and P. Sarnak, Chebyshev's bias, Experimental Mathematics, Volume 3, Issue 3, 1994, pp. 173-197.
Eric Weisstein's World of Mathematics, Prime Quadratic Effect

A297356 Values of n for which pi_{12,7}(p_n) - pi_{12,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

919096512484, 919096512490, 919096512492, 919096512496, 919096512500, 919096512504, 919096512517, 919096512519, 919096512648, 919096512655, 919096512662, 919096512718, 919096512725, 919096512729, 919096512741, 919096512744, 919096512747, 919096512753, 919096512798, 919096512802

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Dec 29 2017

nonn

This is a companion sequence to A297357 and includes the values of n for the first discovered sign-changing zone for pi_{12,7}(p) - pi_{12,1}(p) prime race. The full sequence checked up to 10^14 has 55596 terms (see b-file).

Sergei D. Shchebetov, Table of n, a(n) for n = 1..55596
C. Bays, K. Ford, R. H. Hudson and M. Rubinstein, Zeros of Dirichlet L-functions near the real axis and Chebyshev's bias, J. Number Theory 87 (2001), pp. 54-76.
A. Granville and G. Martin, Prime Number Races, Amer. Math. Monthly 113 (2006), no. 1, 1-33.
M. Rubinstein and P. Sarnak, Chebyshev's bias, Experimental Mathematics, Volume 3, Issue 3, 1994, pp. 173-197.
Eric Weisstein's World of Mathematics, Prime Quadratic Effect

A297355 Primes p for which pi_{12,5}(p) - pi_{12,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Original entry on oeis.org

25726067172577, 25726067172857, 25726067173321, 25726067173441, 25726067174389, 25726067174461, 25726067174653, 25726067174761, 25726067175961, 25726067176549, 25726067176669, 25726067176993, 25726067177149, 25726067177429, 25726067177449, 25726067177593, 25726067177617, 25726067177689, 25726067177801, 25726067178013

Offset: 1

Andrey S. Shchebetov and Sergei D. Shchebetov, Dec 29 2017

nonn

This is a companion sequence to A297354 and includes the first discovered sign-changing zone for pi_{12,5}(p) - pi_{12,1}(p) prime race. The full sequence checked up to 10^14 has 8399 terms (see b-file).

Sergei D. Shchebetov, Table of n, a(n) for n = 1..8399
C. Bays and R. H. Hudson, Details of the first region of integers x with pi_{3,2} (x) < pi_{3,1}(x), Math. Comp. 32 (1978), 571-576.
C. Bays, K. Ford, R. H. Hudson and M. Rubinstein, Zeros of Dirichlet L-functions near the real axis and Chebyshev's bias, J. Number Theory 87 (2001), pp. 54-76.
A. Granville and G. Martin, Prime Number Races, Amer. Math. Monthly 113 (2006), no. 1, 1-33.
M. Rubinstein and P. Sarnak, Chebyshev's bias, Experimental Mathematics, Volume 3, Issue 3, 1994, pp. 173-197.
Eric Weisstein's World of Mathematics, Prime Quadratic Effect

Cf. A007350, A007351, A038691, A051024, A066520, A096628, A096447, A096448, A199547, A297354.

cp's OEIS Frontend

User: Sergei D. Shchebetov

A353185 Numbers which require exactly 289 'Reverse and Add' steps to reach a palindrome.

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A326414 Numbers which require exactly 288 'Reverse and Add' steps to reach a palindrome.

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A298821 Primes p for which pi_{24,19}(p) - pi_{24,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

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A298820 Values of n for which pi_{24,19}(p_n) - pi_{24,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

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A297450 Primes p for which pi_{24,17}(p) - pi_{24,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

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A297449 Values of n for which pi_{24,17}(p_n) - pi_{24,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

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A297447 Values of n for which pi_{8,5}(p_n) - pi_{8,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

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A297357 Primes p for which pi_{12,7}(p) - pi_{12,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

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A297356 Values of n for which pi_{12,7}(p_n) - pi_{12,1}(p_n) = -1, where p_n is the n-th prime and pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

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A297355 Primes p for which pi_{12,5}(p) - pi_{12,1}(p) = -1, where pi_{m,a}(x) is the number of primes <= x which are congruent to a (mod m).

Views

Author

Keywords

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