A255419 Row 9 of Ludic array A255127.

25, 167, 311, 457, 599, 745, 883, 1033, 1181, 1321, 1469, 1615, 1753, 1903, 2041, 2191, 2339, 2483, 2623, 2773, 2911, 3059, 3211, 3353, 3493, 3637, 3781, 3929, 4067, 4217, 4367, 4507, 4657, 4795, 4937, 5087, 5227, 5377, 5527, 5665, 5813, 5957, 6101, 6241, 6389, 6535, 6683, 6821, 6971, 7111

Offset: 1

Author

Antti Karttunen, Feb 22 2015

Keywords

• nonn

Comments

This is the first row in A255127 that starts with a composite number.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10001

Crossrefs

Row 9 of A255127. See A255413 - A255418 for rows 3 through 8.

Programs

PARI

my(L=vector(97847750, x, 3*x+1+x%2), m(n, k)=2^(n\/k*k)\(2^k-1)); for(i=3, 8, L=vecextract(L, 2^#L-m(#L, L[1])-1)); L255419=vecextract(L, m(#L, L[1]));
\\ If only terms up to N < P are needed, the vector L above can be chosen shorter
A255419(n, P=2027520)=n--\P*293543250 + L255419[n%P+1] \\ M. F. Hasler, Nov 17 2024

Python

# if only terms up to a smaller limit S are needed, then S can be decreased
def A255419(n, S=293543250, P=2027520):
    try: n -= 1; return A255419.L[n]
    except IndexError: return A255419.L[n%P] + n//P*S
    except AttributeError: L = [x+5-x%2 for x in range(0, S, 3)]
    while (k:=L[0]) < 25: L = [x for i, x in enumerate(L) if i%k]
    A255419.L = L[::k]; return A255419(n+1) # M. F. Hasler, Nov 17 2024

Scheme

(define (A255419 n) (A255127bi 9 n)) ;; Code for A255127bi given in A255127.

Formula

a(n) = a(n-P) + S = a((n-1)%P + 1) + S*floor((n-1)/P) with period P = 2027520 = A377469(9) and shift S = 293543250 = A376237(10). - M. F. Hasler, Nov 17 2024