A290148 -id:A290148 - cp's OEIS frontend

A381225 Index of first occurrence of n in A290148.

1, 2, 3, 4, 5, 6, 7, 8, 9, 91, 101, 12, 22, 32, 42, 52, 62, 72, 82, 92, 201, 13, 23, 33, 43, 53, 63, 73, 83, 93, 301, 14, 24, 34, 44, 54, 64, 74, 84, 94, 401, 15, 25, 35, 45, 55, 65, 75, 85, 95, 501, 16, 26, 36, 46, 56, 66, 76, 86, 96, 601, 17, 27, 37, 47, 57, 67, 77, 87, 97, 701, 18, 28, 38, 48, 58, 68, 78, 88, 98, 801, 19, 29, 39

Offset: 0

N. J. A. Sloane, Feb 23 2025

Every number >= 0 appears in A290148, and in fact a(n) <= 10*n+1.

N. J. A. Sloane, Table of n, a(n) for n = 0..1999

f. A290148.

A381224 a(n) is the integer resulting from the concatenation of the unit digit of prime(n-1) to the digits of prime(n) without its own unit digit.

Original entry on oeis.org

0, 2, 3, 5, 71, 11, 31, 71, 92, 32, 93, 13, 74, 14, 34, 75, 35, 96, 16, 77, 17, 37, 98, 38, 99, 710, 110, 310, 710, 911, 312, 713, 113, 713, 914, 915, 115, 716, 316, 717, 317, 918, 119, 119, 319, 719, 921, 122, 322, 722, 923, 323, 924, 125, 125, 726, 326, 927, 127, 728, 128, 329, 330, 731, 131, 331, 733, 133, 734, 734, 935, 335

Offset: 1

N. J. A. Sloane, Feb 22 2025

Take list of primes and move the right-most digit of each term to the start of the next term.

Inspired by Eric Angelini and Carole Dubois's A339467.

			Starting from
   2, 3, 5, 7, 11, 13, 17, 19, ...
we get
   0, 2, 3, 5, 71, 11, 31, 71, ...

N. J. A. Sloane, Table of n, a(n) for n = 1..10000

Cf. A000040, A032759, A290148, A339467.

a381224 := proc(n) local i,p;
if n=1 then i:=0; else i:=(ithprime(n-1) mod 10); fi;
p:=ithprime(n);
i * 10^ilog10(p) + floor(p/10);
end;

from sympy import prime
def a(n): return 0 if n == 1 else int(str(prime(n-1)%10)+ str(prime(n))[:-1])
print([a(n) for n in range(1, 73)]) # Michael S. Branicky, Feb 22 2025

cp's OEIS Frontend

A381225 Index of first occurrence of n in A290148.

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A381224 a(n) is the integer resulting from the concatenation of the unit digit of prime(n-1) to the digits of prime(n) without its own unit digit.

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