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.

A248138 Consider the partition of consecutive evil numbers (A001969) into minimal blocks such that concatenation of numbers in each block is an odious number (A000069). Sequence lists numbers of evil numbers in each block.

Original entry on oeis.org

3, 2, 2, 3, 2, 3, 4, 2, 2, 5, 2, 5, 3, 2, 2, 2, 2, 2, 6, 4, 3, 6, 4, 7, 4, 5, 3, 4, 3, 2, 3, 3, 4, 2, 2, 2, 2, 2, 2, 2, 4, 3, 3, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 5, 2, 3, 5, 2, 3, 3, 6, 2, 4, 5, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 4, 3, 2, 2, 2, 3
Offset: 1

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Author

Keywords

Comments

The blocks of consecutive evil numbers of the partition are
0,3,5| 6,9| 10,12| 15,17,18| 20,23| 24,27,29| 30,33,34,36| 39,40| 43,45| 46,48,51,53,54| 57,58| 60,63,65,66,68|, etc.

Crossrefs

A248009 Partition of the positive odd integers into minimal blocks such that the concatenation of the numbers in each block is an evil number (A001969). Sequence lists the evil numbers obtained in this way.

Original entry on oeis.org

135, 7911, 131517, 19212325272931, 33, 35373941, 43, 45, 4749, 51, 53, 5557, 596163, 65, 676971, 737577, 798183, 85, 8789, 9193, 95, 9799101103105, 107109, 111, 113, 115117119, 121123125127129, 131133, 135, 137139, 141, 143145147, 149, 151153155157, 159
Offset: 1

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Author

Vladimir Shevelev, Oct 05 2014

Keywords

Comments

The numbers of the consecutive positive odd integers in the blocks of the partition are 3,3,3,7,1,4,1,1,2,1,1,2,3,1,3,3,3,1,2,2,...

Examples

			a(1)=135, since 1 and 13 are odious numbers, while 135 is evil.
		

Crossrefs

Programs

  • PARI
    lista(nn) = {s = ""; forstep(n=1, nn, 2, ns = concat(s, Str(n)); if ((hammingweight(eval(ns)) % 2) == 0, print1(ns, ", "); s = "", s = ns););} \\ Michel Marcus, Oct 09 2014

Extensions

More terms from Peter J. C. Moses, Oct 09 2014

A248171 Partition of the positive integers on minimal blocks such that concatenation of numbers in each block is an evil number (A001969). Sequence lists the evil numbers obtained in this way.

Original entry on oeis.org

12, 3, 45, 6, 78, 9, 10, 1112, 1314, 15, 161718, 1920, 2122, 23, 24, 2526, 27, 2829, 30, 3132, 33, 34, 3536, 37383940, 414243, 4445464748, 495051, 52535455, 5657, 58, 5960, 6162, 63, 646566, 6768, 6970, 71, 72, 7374, 75, 7677787980, 818283, 8485868788, 89, 90
Offset: 1

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Author

Vladimir Shevelev, Oct 03 2014

Keywords

Comments

The numbers of the consecutive positive integers over blocks of the partition are 2,1,2,1,2,1,1,2,2,1,3,2,2,1,1,2,1,...

Crossrefs

Cf. A000069 (odious), A001969 (evil), A248009, A248138, A248140, A248172 (similar, with odious).

Programs

  • Python
    from itertools import count
    def evil(n): return bin(n)[2:].count('1') % 2 == 0
    def aupton(terms):
        alst, t = [], 0
        for k in count(1):
            t = int(str(t) + str(k))
            if evil(t):
                alst.append(t)
                t = 0
                if len(alst) >= terms: return alst
    print(aupton(45)) # Michael S. Branicky, Dec 03 2021

Extensions

More terms from Peter J. C. Moses, Oct 04 2014

A248172 Partition of the positive integers on minimal blocks such that concatenation of numbers in each block is an odious number (A000069). Sequence lists the odious numbers obtained in this way.

Original entry on oeis.org

1, 2, 345, 67, 8, 9101112, 13, 14, 1516, 1718, 19, 202122232425, 26, 2728, 2930, 31, 32, 3334, 35, 3637, 38, 3940, 41, 42, 4344454647, 4849, 50, 5152, 5354, 55, 56, 5758, 59, 6061, 62, 6364, 6566, 67, 686970, 7172737475, 76, 7778, 79, 808182, 8384, 8586, 87
Offset: 1

Views

Author

Vladimir Shevelev, Oct 03 2014

Keywords

Comments

The numbers of the consecutive positive integers over blocks of the partition are 1,1,3,2,1,4,1,1,2,2,1,6,1,2,2,1,1,2,1,...

Crossrefs

Cf. A000069 (odious), A001969 (evil), A248009, A248138, A248140, A248171 (similar, with evil).

Extensions

More terms from Peter J. C. Moses, Oct 04 2014
Showing 1-4 of 4 results.