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.

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A364498 Odd numbers k such that k divides A243071(k).

Original entry on oeis.org

1, 3, 43, 1177, 3503, 49477, 169413, 428015, 4394113, 33228911
Offset: 1

Views

Author

Antti Karttunen, Jul 27 2023

Keywords

Comments

Primes p present are those that occur as factors of (2^A000720(p))-1: 3, 43, 49477, 4394113, 33228911, ...

Examples

			1177 = 11 * 107, with A243071(1177) = 536870895 = 3*5*11*47*107*647, therefore 1177 is present. Note that 536870895 = 11111111111111111111111101111 in binary, with four 1-bits at the least significant end, followed by 0, and then 24 more 1-bits at the most significant end, so A163511(536870895) = A000040(1+4) * A000040(4+24) = 11 * 107.
		

Crossrefs

Odd terms in A364497.

Programs

  • PARI
    A054429(n) = ((3<<#binary(n\2))-n-1); \\ From A054429
    A156552(n) = { my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
    A243071(n) = if(n<=2, n-1, A054429(A156552(n)));
    isA364498(n) = ((n%2)&&!(A243071(n)%n));

Extensions

a(10) from Chai Wah Wu, Jul 27 2023

A297161 Restricted growth sequence transform of A297171, which is Möbius transform of A243071.

Original entry on oeis.org

1, 2, 3, 2, 4, 5, 6, 5, 5, 7, 8, 9, 10, 11, 3, 12, 13, 5, 14, 15, 16, 17, 18, 19, 12, 20, 12, 21, 22, 12, 23, 24, 25, 26, 9, 12, 27, 28, 29, 30, 31, 32, 33, 34, 19, 35, 36, 37, 24, 12, 38, 39, 40, 12, 41, 42, 43, 44, 45, 4, 46, 47, 30, 48, 49, 50, 51, 52, 53, 7, 54, 24, 55, 56, 12, 57, 58, 59, 60, 61, 24, 62, 63, 64, 65, 66, 67, 68, 69, 19
Offset: 1

Views

Author

Antti Karttunen, Dec 27 2017

Keywords

Crossrefs

Programs

  • PARI
    up_to = 8192;
    rgs_transform(invec) = { my(occurrences = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(occurrences,invec[i]), my(pp = mapget(occurrences, invec[i])); outvec[i] = outvec[pp] , mapput(occurrences,invec[i],i); outvec[i] = u; u++ )); outvec; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A243071(n) = if(n<=2, n-1, if(!(n%2), 2*A243071(n/2), 1+(2*A243071(A064989(n)))));
    A297171(n) = sumdiv(n,d,moebius(n/d)*A243071(d));
    write_to_bfile(1,rgs_transform(vector(up_to,n,A297171(n))),"b297161.txt");

A334859 a(n) = A243071(A225546(n)).

Original entry on oeis.org

0, 1, 2, 3, 8, 4, 128, 6, 5, 16, 32768, 12, 2147483648, 256, 32, 7, 9223372036854775808, 10, 170141183460469231731687303715884105728, 48, 512, 65536, 57896044618658097711785492504343953926634992332820282019728792003956564819968, 24, 17, 4294967296, 20, 768
Offset: 1

Views

Author

Antti Karttunen, Jun 08 2020

Keywords

Crossrefs

Inverse permutation of A334860. Composition of permutations A225546 and A243071, and also of A054429 and A334865.

Formula

a(n) = A243071(A225546(n)).
a(n) = A054429(A334865(n)).
For n >= 1, A000120(a(n)) = A299090(n).
For n > 1, A070939(a(n)) = A334871(n).

A364256 a(n) = gcd(n, A243071(n)).

Original entry on oeis.org

1, 1, 3, 2, 1, 6, 1, 4, 1, 2, 1, 12, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2, 1, 24, 1, 2, 9, 4, 1, 2, 1, 16, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 43, 4, 5, 2, 1, 48, 1, 2, 1, 4, 1, 18, 1, 8, 1, 2, 1, 4, 1, 2, 3, 32, 1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 3, 4, 11, 2, 1, 16, 1, 2, 1, 4, 1, 86, 1, 8, 1, 10, 7, 4, 1, 2, 1, 96, 1, 2, 11, 4
Offset: 1

Views

Author

Antti Karttunen, Jul 17 2023

Keywords

Comments

Primes p such that a(p) = p are those that occur as factors of (2^A000720(p))-1: 3, 43, 49477. Are there any more of them?

Crossrefs

Cf. A243071.
Cf. also A364254, A364255.

Programs

  • PARI
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A243071(n) = if(n<=2, n-1, if(!(n%2), 2*A243071(n/2), 1+(2*A243071(A064989(n)))));
    A364256(n) = gcd(n, A243071(n));

A364290 Numbers k such that A243071(k) < k.

Original entry on oeis.org

1, 2, 4, 8, 9, 15, 16, 18, 25, 27, 30, 32, 35, 36, 45, 49, 50, 54, 60, 63, 64, 70, 72, 75, 77, 81, 90, 98, 100, 105, 108, 120, 121, 125, 126, 128, 135, 140, 143, 144, 147, 150, 154, 162, 165, 169, 175, 180, 189, 196, 200, 210, 216, 225, 231, 240, 242, 243, 245, 250, 252, 256, 270, 273, 275, 280, 286, 288, 289, 294
Offset: 1

Views

Author

Antti Karttunen, Jul 25 2023

Keywords

Comments

If k is present, then 2*k is also present, and vice versa.
361 = 19^2 is the first square that is not present in this sequence.

Crossrefs

Positions of strictly positive terms in A364288.
Subsequence of A364291.
Cf. A243071, A364289 (complement).
Cf. also A364287.

Programs

A253892 Permutation of natural numbers: a(n) = A243071(A245612(n)).

Original entry on oeis.org

0, 1, 7, 3, 30, 63, 4, 2, 8191, 57, 510, 11, 511, 10, 31, 6, 524286, 36893488147419103231, 131068, 65532, 1073741823, 16381, 8190, 262143, 508, 248, 65535, 125, 16, 60, 127, 15, 4194299, 633825300114114700748351602685, 2097134, 200867255532373784442745261542645325315275374222849104412671, 10141204801825835211973625643007, 442, 268435451, 32754, 190
Offset: 0

Views

Author

Antti Karttunen, Jan 17 2015

Keywords

Crossrefs

Programs

Formula

a(n) = A243071(A245612(n)).
As a composition of other related permutations:
a(n) = A054429(A253792(A054429(n))).

A332811 a(n) = A243071(A332808(n)).

Original entry on oeis.org

0, 1, 3, 2, 7, 6, 15, 4, 5, 14, 63, 12, 31, 30, 13, 8, 127, 10, 255, 28, 29, 126, 1023, 24, 11, 62, 9, 60, 511, 26, 4095, 16, 125, 254, 27, 20, 2047, 510, 61, 56, 8191, 58, 16383, 252, 25, 2046, 65535, 48, 23, 22, 253, 124, 32767, 18, 123, 120, 509, 1022, 262143, 52, 131071, 8190, 57, 32, 59, 250, 1048575, 508, 2045, 54, 4194303, 40, 524287, 4094, 21
Offset: 1

Views

Author

Antti Karttunen, Mar 05 2020

Keywords

Crossrefs

Cf. A332817 (inverse permutation).
Cf. also A332215.

Programs

  • PARI
    up_to = 26927;
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A243071(n) = if(n<=2, n-1, if(!(n%2), 2*A243071(n/2), 1+(2*A243071(A064989(n)))));
    A332806list(up_to) = { my(v=vector(2), xs=Map(), lista=List([]), p,q,u); v[2] = 3; v[1] = 5; mapput(xs,1,1); mapput(xs,2,2); mapput(xs,3,3);  for(n=4,up_to, p = v[2-(n%2)]; q = nextprime(1+p); while(q%4 != p%4, q=nextprime(1+q)); v[2-(n%2)] = q; mapput(xs,primepi(q),n)); for(i=1, oo, if(!mapisdefined(xs, i, &u), return(Vec(lista)), listput(lista, prime(u)))); };
    v332806 = A332806list(up_to);
    A332806(n) = v332806[n];
    A332808(n) = { my(f=factor(n)); f[,1] = apply(A332806,apply(primepi,f[,1])); factorback(f); };
    A332811(n) = A243071(A332808(n));

Formula

a(n) = A243071(A332808(n)).
For n > 1, a(n) = A054429(A332816(n)).
a(n) = A332895(n) + A332896(n).
a(n) = A332895(n) OR A332896(n) = A332895(n) XOR A332896(n).
A000120(a(n)) = A332899(n).

A364291 Numbers k such that A243071(k) <= k.

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 9, 12, 15, 16, 18, 24, 25, 27, 30, 32, 35, 36, 45, 48, 49, 50, 54, 60, 63, 64, 70, 72, 75, 77, 81, 90, 96, 98, 100, 105, 108, 120, 121, 125, 126, 128, 135, 140, 143, 144, 147, 150, 154, 162, 165, 169, 175, 180, 189, 192, 196, 200, 210, 216, 225, 231, 240, 242, 243, 245, 250, 252, 256, 270, 273
Offset: 1

Views

Author

Antti Karttunen, Jul 25 2023

Keywords

Comments

If k is present, then 2*k is also present, and vice versa.

Crossrefs

Positions of nonnegative terms in A364288.
Cf. A007283, A364290 (subsequences).
Cf. A243071.
Cf. also A364287.

Programs

A366276 Permutation of nonnegative integers: a(n) = A057889(A243071(n)).

Original entry on oeis.org

0, 1, 3, 2, 7, 6, 15, 4, 5, 14, 31, 12, 63, 30, 11, 8, 127, 10, 255, 28, 23, 62, 511, 24, 13, 126, 9, 60, 1023, 22, 2047, 16, 47, 254, 27, 20, 4095, 510, 95, 56, 8191, 46, 16383, 124, 19, 1022, 32767, 48, 29, 26, 191, 252, 65535, 18, 55, 120, 383, 2046, 131071, 44, 262143, 4094, 39, 32, 111, 94, 524287, 508, 767, 54
Offset: 1

Views

Author

Antti Karttunen, Oct 06 2023

Keywords

Crossrefs

Cf. A057889, A243071, A366275 (inverse map), A366277 (fixed points of map n -> a(n)).

Programs

  • PARI
    A030101(n) = if(n<1,0,subst(Polrev(binary(n)),x,2));
    A057889(n) = if(!n,n,A030101(n/(2^valuation(n,2))) * (2^valuation(n, 2)));
    A243071(n) = if(n<=2, n-1, my(f=factor(n), p, p2=1, res=0); for(i=1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p*p2*(2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); ((3<<#binary(res\2))-res-1)); \\ (Combining programs given in A156552 and A054429)
    A366276(n) = A057889(A243071(n));

A275715 Permutation of natural numbers: a(n) = A243071(A249823(n)).

Original entry on oeis.org

0, 1, 3, 7, 15, 31, 63, 127, 2, 255, 511, 6, 1023, 2047, 4095, 8191, 5, 16383, 14, 32767, 65535, 30, 131071, 262143, 524287, 13, 1048575, 2097151, 62, 4194303, 29, 126, 8388607, 16777215, 33554431, 67108863, 134217727, 268435455, 254, 61, 11, 4, 536870911, 1073741823, 125, 2147483647, 4294967295, 27, 510, 8589934591
Offset: 1

Views

Author

Antti Karttunen, Aug 06 2016

Keywords

Comments

Note the indexing: the domain starts from 1, while the range includes also zero.

Crossrefs

Inverse: A275716.
Related or similar permutations: A243071, A249823, A245611.
Cf. also A273664, A273669.

Programs

Formula

a(n) = A243071(A249823(n)).
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